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AUSCERT External Security Bulletin Redistribution
ESB-2021.3314
Cisco Email Security Appliance URL Filtering Bypass Vulnerability
7 October 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Email Security Appliance
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Reduced Security -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2021-1534
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-url-bypass-sGcfsDrp
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Cisco Email Security Appliance URL Filtering Bypass Vulnerability
Priority: Medium
Advisory ID: cisco-sa-esa-url-bypass-sGcfsDrp
First Published: 2021 October 6 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvx60178
CVE Names: CVE-2021-1534
CWEs: CWE-20
Summary
o A vulnerability in the antispam protection mechanisms of Cisco AsyncOS
Software for Cisco Email Security Appliance (ESA) could allow an
unauthenticated, remote attacker to bypass the URL reputation filters on an
affected device.
This vulnerability is due to improper processing of URLs. An attacker could
exploit this vulnerability by crafting a URL in a particular way. A
successful exploit could allow the attacker to bypass the URL reputation
filters that are configured for an affected device, which could allow
malicious URLs to pass through the 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-esa-url-bypass-sGcfsDrp
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected Cisco AsyncOS
Software for Cisco ESA releases earlier than Release 14.0.1.
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.
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.
Fixed Releases
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.
Cisco AsyncOS Software for Cisco Email Security First Fixed Release
Appliance
Earlier than 14.0 Migrate to a fixed
release.
14.0 14.0.1
The fixed release is not available from the Software Center at Cisco.com.
Administrators can upgrade the software through the GUI or CLI.
In most cases, the software can be upgraded over the network by using the
System Upgrade options in the web interface of Cisco ESA. To upgrade a
device using the web interface, do the following:
1. Choose System Administration > System Upgrade .
2. Click Upgrade Options .
3. Choose Download and Install .
4. Choose the appropriate release.
5. In the Upgrade Preparation area, choose the appropriate options.
6. Click Proceed to begin the upgrade. A progress bar will display the
status of the upgrade. After the upgrade is complete, the device will
reboot.
The Cisco Product Security Incident Response Team (PSIRT) validates only
the affected and fixed release information that is documented in this
advisory.
Exploitation and Public Announcements
o The Cisco 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.
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-esa-url-bypass-sGcfsDrp
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2021-OCT-06 |
+----------+---------------------------+----------+--------+--------------+
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