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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                               ESB-2021.1035
              Cisco IOS XE Software multiple vulnerabilities
                               25 March 2021

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Cisco IOS XE Software
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Execute Arbitrary Code/Commands -- Existing Account
                   Reduced Security                -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-1398 CVE-2021-1390 CVE-2021-1381
                   CVE-2021-1376 CVE-2021-1375 

Original Bulletin: 
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-OFP-6Nezgn7b
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fast-Zqr6DD5
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-ACE-75K3bRWe
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-BLKH-Ouvrnf2s

Comment: This bulletin contains four (4) Cisco Systems security advisories.

- --------------------------BEGIN INCLUDED TEXT--------------------

Cisco IOS XE Software Local Privilege Escalation Vulnerability

Priority:        Medium
Advisory ID:     cisco-sa-XE-OFP-6Nezgn7b
First Published: 2021 March 24 16:00 GMT
Version 1.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvu78930
CVE Names:       CVE-2021-1390
CWEs:            CWE-123

Summary

  o A vulnerability in one of the diagnostic test CLI commands of Cisco IOS XE
    Software could allow an authenticated, local attacker to execute arbitrary
    code on an affected device. To exploit this vulnerability, the attacker
    would need to have valid user credentials at privilege level 15.

    This vulnerability exists because the affected software permits
    modification of the run-time memory of an affected device under specific
    circumstances. An attacker could exploit this vulnerability by
    authenticating to the affected device and issuing a specific diagnostic
    test command at the CLI. A successful exploit could trigger a logic error
    in the code that was designed to restrict run-time memory modifications.
    The attacker could take advantage of this logic error to overwrite system
    memory locations and execute arbitrary code on the underlying Linux
    operating system (OS) of the affected device.

    Cisco has released software updates that address this vulnerability. There
    are no workarounds that address this vulnerability.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-OFP-6Nezgn7b

Affected Products

  o Vulnerable Products

    At the time of publication, this vulnerability affected the following Cisco
    devices if they were running a vulnerable release of Cisco IOS XE Software:

       Catalyst IE3200 Rugged Series
       Catalyst IE3300 Rugged Series
       Catalyst IE3400 Rugged Series
       Catalyst IE3400 Heavy Duty Series
       Embedded Services 3300 Series Switches

    For information about which Cisco software releases are vulnerable, see the
    Fixed Software section of this advisory.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

    Cisco has confirmed that this vulnerability does not affect the following
    Cisco products:

       IOS Software
       IOS XR Software
       NX-OS Software

Workarounds

  o There are no workarounds that address this vulnerability.

Fixed Software

  o Cisco has released free software updates that address the vulnerability
    described in this advisory. Customers may only install and expect support
    for software versions and feature sets for which they have purchased a
    license. By installing, downloading, accessing, or otherwise using such
    software upgrades, customers agree to follow the terms of the Cisco
    software license:
    https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

    Additionally, customers may only download software for which they have a
    valid license, procured from Cisco directly, or through a Cisco authorized
    reseller or partner. In most cases this will be a maintenance upgrade to
    software that was previously purchased. Free security software updates do
    not entitle customers to a new software license, additional software
    feature sets, or major revision upgrades.

    When considering software upgrades , customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories page , to determine exposure and a complete
    upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    contain sufficient memory and confirm that current hardware and software
    configurations will continue to be supported properly by the new release.
    If the information is not clear, customers are advised to contact the Cisco
    Technical Assistance Center (TAC) or their contracted maintenance
    providers.

    Customers Without Service Contracts

    Customers who purchase directly from Cisco but do not hold a Cisco service
    contract and customers who make purchases through third-party vendors but
    are unsuccessful in obtaining fixed software through their point of sale
    should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c
    /en/us/support/web/tsd-cisco-worldwide-contacts.html

    Customers should have the product serial number available and be prepared
    to provide the URL of this advisory as evidence of entitlement to a free
    upgrade.

    Cisco IOS and IOS XE Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    and IOS XE Software, Cisco provides the Cisco Software Checker to identify
    any Cisco Security Advisories that impact a specific software release and
    the earliest release that fixes the vulnerabilities described in each
    advisory ("First Fixed"). If applicable, the tool also returns the earliest
    release that fixes all the vulnerabilities described in all the advisories
    identified ("Combined First Fixed").

    Customers can use the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories, a specific advisory, or all advisories in
    the most recent bundled publication.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
    Software release-for example, 15.1(4)M2 or 3.13.8S.

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker on Cisco.com and check the Medium check box in the
    drop-down list under Impact Rating when customizing a search.

    For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
    releases, refer to the Cisco IOS XE 2 Release Notes , Cisco IOS XE 3S
    Release Notes , or Cisco IOS XE 3SG Release Notes , depending on the Cisco
    IOS XE Software release.

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
    any public announcements or malicious use of the vulnerability that is
    described in this advisory.

Source

  o This vulnerability was found during internal security testing by X.B. of
    the Cisco Advanced Security Initiatives Group (ASIG).

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy . This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-OFP-6Nezgn7b

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2021-MAR-24  |
    +----------+---------------------------+----------+--------+--------------+


- --------------------------------------------------------------------------------


Cisco IOS XE Software Fast Reload Vulnerabilities

Priority:        High
Advisory ID:     cisco-sa-fast-Zqr6DD5
First Published: 2021 March 24 16:00 GMT
Version 1.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvr71885 CSCvu85472
CVE Names:       CVE-2021-1375 CVE-2021-1376
CWEs:            CWE-347

CVSS Score:
6.7  AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X

Summary

  o Multiple vulnerabilities in the fast reload feature of Cisco IOS XE
    Software running on Cisco Catalyst 3850, Cisco Catalyst 9300, and Cisco
    Catalyst 9300L Series Switches could allow an authenticated, local attacker
    to either execute arbitrary code on the underlying operating system,
    install and boot a malicious software image, or execute unsigned binaries
    on an affected device.

    These vulnerabilities are due to improper checks performed by system boot
    routines. To exploit these vulnerabilities, the attacker would need
    privileged access to the CLI of the device. A successful exploit could
    allow the attacker to either execute arbitrary code on the underlying
    operating system or execute unsigned code and bypass the image verification
    check part of the secure boot process.

    For more information about these vulnerabilities, see the Details section
    of this advisory.

    Cisco has released software updates that address these vulnerabilities.
    There are no workarounds that address these vulnerabilities.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fast-Zqr6DD5

    This advisory is part of the March 2021 release of the Cisco IOS and IOS XE
    Software Security Advisory Bundled Publication. For a complete list of the
    advisories and links to them, see Cisco Event Response: March 2021
    Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
    Publication .

Affected Products

  o Vulnerable Products

    These vulnerabilities affect Cisco Catalyst 3850, Cisco Catalyst 9300, and
    Cisco Catalyst 9300L Series Switches if they are running a vulnerable
    release of Cisco IOS XE Software.

    For information about which Cisco software releases are vulnerable, see the
    Fixed Software section of this advisory.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by these vulnerabilities.

    Cisco has confirmed that these vulnerabilities do not affect the following
    Cisco products:

       IOS Software
       IOS XR Software
       NX-OS Software

Details

  o These vulnerabilities are not dependent on one another. Exploitation of one
    of the vulnerabilities is not required to exploit the other vulnerability.
    In addition, a software release that is affected by one of the
    vulnerabilities may not be affected by the other vulnerability.

    Details about the vulnerabilities are as follows.

    CVE-2021-1375: Cisco IOS XE Software Fast Reload Arbitrary Code Execution
    Vulnerability

    A vulnerability in the fast reload feature of Cisco IOS XE Software running
    on Cisco Catalyst 3850, Cisco Catalyst 9300, and Cisco Catalyst 9300L
    Series Switches could allow an authenticated, local attacker to execute
    unsigned code at system boot time.

    This vulnerability is due to incorrect validations of parameters passed to
    a configuration file that is executed when the device boots up. An attacker
    could exploit this vulnerability by tampering with a configuration file
    stored on a device. A successful exploit could allow the attacker to
    execute unsigned code at boot time and bypass the software image
    verification check part of the secure boot process of an affected device.

    Cisco has released software updates that address this vulnerability. There
    are no workarounds that address this vulnerability.

    Bug ID(s): CSCvr71885
    CVE ID: CVE-2021-1375
    Security Impact Rating (SIR): High
    CVSS Base Score: 6.7
    CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

    CVE-2021-1376: Cisco IOS XE Software Fast Reload Arbitrary Code Execution
    Vulnerability

    A vulnerability in the fast reload feature of Cisco IOS XE Software running
    on Cisco Catalyst 3850, Cisco Catalyst 9300, and Cisco Catalyst 9300L
    Series Switches could allow an authenticated, local attacker to execute
    arbitrary code on the underlying operating system of an affected device.

    This vulnerability is due to an improper check on the area of code that
    manages the verification of boot configuration files during the initial
    fast reload boot process. To exploit this vulnerability, the attacker would
    need privileged access to the CLI of the device. A successful exploit could
    allow the attacker to execute arbitrary code on the underlying operating
    system.

    Bug ID(s): CSCvu85472
    CVE ID: CVE-2021-1376
    Security Impact Rating (SIR): Medium
    CVSS Base Score: 5.1
    CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:N

Workarounds

  o There are no workarounds that address these vulnerabilities.

Fixed Software

  o Cisco has released free software updates that address the vulnerabilities
    described in this advisory. Customers may only install and expect support
    for software versions and feature sets for which they have purchased a
    license. By installing, downloading, accessing, or otherwise using such
    software upgrades, customers agree to follow the terms of the Cisco
    software license: https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

    Additionally, customers may only download software for which they have a
    valid license, procured from Cisco directly, or through a Cisco authorized
    reseller or partner. In most cases this will be a maintenance upgrade to
    software that was previously purchased. Free security software updates do
    not entitle customers to a new software license, additional software
    feature sets, or major revision upgrades.

    When considering software upgrades , customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories and Alerts page , to determine exposure and a
    complete upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    contain sufficient memory and confirm that current hardware and software
    configurations will continue to be supported properly by the new release.
    If the information is not clear, customers are advised to contact the Cisco
    Technical Assistance Center (TAC) or their contracted maintenance
    providers.

    Customers Without Service Contracts

    Customers who purchase directly from Cisco but do not hold a Cisco service
    contract and customers who make purchases through third-party vendors but
    are unsuccessful in obtaining fixed software through their point of sale
    should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c
    /en/us/support/web/tsd-cisco-worldwide-contacts.html

    Customers should have the product serial number available and be prepared
    to provide the URL of this advisory as evidence of entitlement to a free
    upgrade.

    Cisco IOS and IOS XE Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    and IOS XE Software, Cisco provides the Cisco Software Checker to identify
    any Cisco Security Advisories that impact a specific software release and
    the earliest release that fixes the vulnerabilities described in each
    advisory ("First Fixed"). If applicable, the tool also returns the earliest
    release that fixes all the vulnerabilities described in all the advisories
    identified ("Combined First Fixed").

    Customers can use the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories, a specific advisory, or all advisories in
    the most recent bundled publication.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
    Software release-for example, 15.1(4)M2 or 3.13.8S.

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker on Cisco.com and check the Medium check box in the
    drop-down list under Impact Rating when customizing a search.

    For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
    releases, refer to the Cisco IOS XE 2 Release Notes , Cisco IOS XE 3S
    Release Notes , or Cisco IOS XE 3SG Release Notes , depending on the Cisco
    IOS XE Software release.

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
    any public announcements or malicious use of the vulnerabilities that are
    described in this advisory.

Source

  o These vulnerabilities were found by Victor Kamensky of Cisco and X.B. of
    Cisco Advanced Initiatives Group (ASIG) during internal security testing.

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy . This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.

Related to This Advisory

  o Cisco Event Response: March 2021 Semiannual Cisco IOS and IOS XE Software
    Security Advisory Bundled Publication

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fast-Zqr6DD5

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2021-MAR-24  |
    +----------+---------------------------+----------+--------+--------------+


- --------------------------------------------------------------------------------


Cisco IOS XE Software Arbitrary Code Execution Vulnerability

Priority:        High
Advisory ID:     cisco-sa-XE-ACE-75K3bRWe
First Published: 2021 March 24 16:00 GMT
Version 1.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvu61463
CVE Names:       CVE-2021-1398
CWEs:            CWE-489

Summary

  o A vulnerability in the boot logic of Cisco IOS XE Software could allow an
    authenticated, local attacker with level 15 privileges or an
    unauthenticated attacker with physical access to execute arbitrary code on
    the underlying Linux operating system of an affected device.

    This vulnerability is due to incorrect validations of specific function
    arguments that are passed to the boot script. An attacker could exploit
    this vulnerability by tampering with a specific file, which an affected
    device would process during the initial boot process. On systems that are
    protected by the Unified Extensible Firmware Interface (UEFI) secure boot
    feature, a successful exploit could allow the attacker to execute unsigned
    code at boot time and bypass the image verification check in the secure
    boot process of the affected device.

    Cisco has released software updates that address this vulnerability. There
    are no workarounds that address this vulnerability.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-ACE-75K3bRWe

    This advisory is part of the March 2021 release of the Cisco IOS and IOS XE
    Software Security Advisory Bundled Publication. For a complete list of the
    advisories and links to them, see Cisco Event Response: March 2021
    Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
    Publication .

Affected Products

  o Vulnerable Products

    This vulnerability affects the following Cisco devices if they are running
    a vulnerable release of Cisco IOS XE Software:

       Integrated Services Virtual Router
       Cloud Services Router 1000V Series

    For information about which Cisco software releases are vulnerable, see the
    Fixed Software section of this advisory.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

    Cisco has confirmed that these vulnerabilities do not affect the following
    Cisco products:

       IOS Software
       IOS XR Software
       NX-OS Software

Workarounds

  o There are no workarounds that address this vulnerability.

Fixed Software

  o Cisco has released free software updates that address the vulnerability
    described in this advisory. Customers may only install and expect support
    for software versions and feature sets for which they have purchased a
    license. By installing, downloading, accessing, or otherwise using such
    software upgrades, customers agree to follow the terms of the Cisco
    software license:
    https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

    Additionally, customers may only download software for which they have a
    valid license, procured from Cisco directly, or through a Cisco authorized
    reseller or partner. In most cases this will be a maintenance upgrade to
    software that was previously purchased. Free security software updates do
    not entitle customers to a new software license, additional software
    feature sets, or major revision upgrades.

    When considering software upgrades , customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories page , to determine exposure and a complete
    upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    contain sufficient memory and confirm that current hardware and software
    configurations will continue to be supported properly by the new release.
    If the information is not clear, customers are advised to contact the Cisco
    Technical Assistance Center (TAC) or their contracted maintenance
    providers.

    Customers Without Service Contracts

    Customers who purchase directly from Cisco but do not hold a Cisco service
    contract and customers who make purchases through third-party vendors but
    are unsuccessful in obtaining fixed software through their point of sale
    should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c
    /en/us/support/web/tsd-cisco-worldwide-contacts.html

    Customers should have the product serial number available and be prepared
    to provide the URL of this advisory as evidence of entitlement to a free
    upgrade.

    Cisco IOS and IOS XE Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    and IOS XE Software, Cisco provides the Cisco Software Checker to identify
    any Cisco Security Advisories that impact a specific software release and
    the earliest release that fixes the vulnerabilities described in each
    advisory ("First Fixed"). If applicable, the tool also returns the earliest
    release that fixes all the vulnerabilities described in all the advisories
    identified ("Combined First Fixed").

    Customers can use the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories, a specific advisory, or all advisories in
    the most recent bundled publication.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
    Software release-for example, 15.1(4)M2 or 3.13.8S.

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker on Cisco.com and check the Medium check box in the
    drop-down list under Impact Rating when customizing a search.

    For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
    releases, refer to the Cisco IOS XE 2 Release Notes , Cisco IOS XE 3S
    Release Notes , or Cisco IOS XE 3SG Release Notes , depending on the Cisco
    IOS XE Software release.

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
    any public announcements or malicious use of the vulnerability that is
    described in this advisory.

Source

  o This vulnerability was found during internal security testing by X.B. of
    the Cisco Advanced Security Initiatives Group (ASIG).

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy . This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.

Related to This Advisory

  o Cisco Event Response: March 2021 Semiannual Cisco IOS and IOS XE Software
    Security Advisory Bundled Publication

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-ACE-75K3bRWe

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2021-MAR-24  |
    +----------+---------------------------+----------+--------+--------------+


- --------------------------------------------------------------------------------


Cisco IOS XE Software Active Debug Code Vulnerability

Priority:        Medium
Advisory ID:     cisco-sa-XE-BLKH-Ouvrnf2s
First Published: 2021 March 24 16:00 GMT
Version 1.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvu78908
CVE Names:       CVE-2021-1381
CWEs:            CWE-489

Summary

  o A vulnerability in Cisco IOS XE Software could allow an authenticated,
    local attacker with high privileges or an unauthenticated attacker with
    physical access to the device to open a debugging console.

    The vulnerability is due to insufficient command authorization
    restrictions. An attacker could exploit this vulnerability by running
    commands on the hardware platform to open a debugging console. A successful
    exploit could allow the attacker to access a debugging console.

    Cisco has released software updates that address this vulnerability. There
    are no workarounds that address this vulnerability.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-BLKH-Ouvrnf2s

Affected Products

  o Vulnerable Products

    At the time of publication, this vulnerability affected the following Cisco
    devices if they were running a vulnerable release of Cisco IOS XE Software:

       IR1101 Integrated Services Routers
       ESR6300 Embedded Series Routers

    For information about which Cisco software releases are vulnerable, see the
    Fixed Software section of this advisory.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

    Cisco has confirmed that this vulnerability does not affect the following
    Cisco products:

       IOS Software
       IOS XR Software
       NX-OS Software

Workarounds

  o There are no workarounds that address this vulnerability.

Fixed Software

  o When considering software upgrades , customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories page , to determine exposure and a complete
    upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    contain sufficient memory and confirm that current hardware and software
    configurations will continue to be supported properly by the new release.
    If the information is not clear, customers are advised to contact the Cisco
    Technical Assistance Center (TAC) or their contracted maintenance
    providers.

    Cisco IOS and IOS XE Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    and IOS XE Software, Cisco provides the Cisco Software Checker to identify
    any Cisco Security Advisories that impact a specific software release and
    the earliest release that fixes the vulnerabilities described in each
    advisory ("First Fixed"). If applicable, the tool also returns the earliest
    release that fixes all the vulnerabilities described in all the advisories
    identified ("Combined First Fixed").

    Customers can use the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories, a specific advisory, or all advisories in
    the most recent bundled publication.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
    Software release-for example, 15.1(4)M2 or 3.13.8S.

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker on Cisco.com and check the Medium check box in the
    drop-down list under Impact Rating when customizing a search.

    For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
    releases, refer to the Cisco IOS XE 2 Release Notes , Cisco IOS XE 3S
    Release Notes , or Cisco IOS XE 3SG Release Notes , depending on the Cisco
    IOS XE Software release.

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
    any public announcements or malicious use of the vulnerability that is
    described in this advisory.

Source

  o This vulnerability was found during internal security testing by X.B. of
    the Cisco Advanced Security Initiatives Group (ASIG).

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy . This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-BLKH-Ouvrnf2s

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2021-MAR-24  |
    +----------+---------------------------+----------+--------+--------------+

- --------------------------END INCLUDED TEXT--------------------

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===========================================================================
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===========================================================================
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