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AUSCERT External Security Bulletin Redistribution
ESB-2021.2875
Cisco UCS Manager Software SSH Sessions Denial of Service Vulnerability
26 August 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: UCS Manager Software
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2021-1592
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ucs-ssh-dos-MgvmyrQy
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Cisco UCS Manager Software SSH Sessions Denial of Service Vulnerability
Priority: Medium
Advisory ID: cisco-sa-ucs-ssh-dos-MgvmyrQy
First Published: 2021 August 25 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvw33513
CVE Names: CVE-2021-1592
CWEs: CWE-664
Summary
o A vulnerability in the way Cisco UCS Manager software handles SSH sessions
could allow an authenticated, remote attacker to cause a denial of service
(DoS) condition on an affected device.
This vulnerability is due to improper resource management for established
SSH sessions. An attacker could exploit this vulnerability by opening a
significant number of SSH sessions on an affected device. A successful
exploit could allow the attacker to cause a crash and restart of internal
Cisco UCS Manager software processes and a temporary loss of access to the
Cisco UCS Manager CLI and web UI.
Note: The attacker must have valid user credentials to authenticate to 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-ucs-ssh-dos-MgvmyrQy
This advisory is part of the August 2021 Cisco FXOS and NX-OS Software
Security Advisory Bundled Publication. For a complete list of the
advisories and links to them, see Cisco Event Response: August 2021 Cisco
FXOS and NX-OS Software Security Advisory Bundled Publication .
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected Cisco UCS 6400
Series Fabric Interconnects devices if they were running a vulnerable
release of Cisco UCS Manager software.
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory. See the Details section in the bug
ID(s) at the top of this advisory for the most complete and current
information.
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:
Firepower 1000 Series
Firepower 2100 Series
Firepower 4100 Series
Firepower 9300 Security Appliances
MDS 9000 Series Multilayer Switches
Nexus 1000 Virtual Edge for VMware vSphere
Nexus 1000V Switch for Microsoft Hyper-V
Nexus 1000V Switch for VMware vSphere
Nexus 3000 Series Switches
Nexus 5500 Platform Switches
Nexus 5600 Platform Switches
Nexus 6000 Series Switches
Nexus 7000 Series Switches
Nexus 9000 Series Fabric Switches in Application Centric Infrastructure
(ACI) mode
Nexus 9000 Series Switches in standalone NX-OS mode
UCS 6200 Series Fabric Interconnects
UCS 6300 Series Fabric Interconnects
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 UCS Software
At the time of publication, the release information in the following table
(s) was accurate. See the Details section in the bug ID(s) at the top of
this advisory for the most complete and current information.
The left column lists Cisco software releases, and the right column
indicates whether a release was affected by the vulnerability described in
this advisory and which release included the fix for this vulnerability.
UCS 6400 Series Fabric Interconnects
Cisco UCS Software Release First Fixed Release for This Vulnerability
4.0 4.0(4m)
4.1 4.1(3e)
4.2 Not vulnerable
Additional Resources
For help determining the best Cisco NX-OS Software release for a Cisco
Nexus Switch, see the following Recommended Releases documents. If a
security advisory recommends a later release, Cisco recommends following
the advisory guidance.
Cisco MDS Series Switches
Cisco Nexus 1000V for VMware Switch
Cisco Nexus 3000 Series Switches
Cisco Nexus 5500 Platform Switches
Cisco Nexus 5600 Platform Switches
Cisco Nexus 6000 Series Switches
Cisco Nexus 7000 Series Switches
Cisco Nexus 9000 Series Switches
Cisco Nexus 9000 Series ACI-Mode Switches
To determine the best release for Cisco UCS Software, see the Recommended
Releases documents in the release notes for the device.
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 by Art Kalmykov of Cisco 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: August 2021 Semiannual Cisco FXOS and NX-OS Software
Security Advisory Bundled Publication
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ucs-ssh-dos-MgvmyrQy
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2021-AUG-25 |
+----------+---------------------------+----------+--------+--------------+
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