Cisco Security Advisory
ClamAV Cascading Style Sheets Image Parsing Error Handling Denial of Service Vulnerability
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CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:X/RL:X/RC:X
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A vulnerability in the HTML Cascading Style Sheets (CSS) module of ClamAV could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
This vulnerability is due to improper error handling when splitting UTF-8 strings. An attacker could exploit this vulnerability by submitting a crafted HTML file to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to terminate the scanning process.
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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-css-Fn4QSZ
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The Vulnerable Products section of this advisory includes Cisco bug IDs for each affected product. The bugs are accessible through the Cisco Bug Search Tool and contain additional platform-specific information, including workarounds (if available) and fixed software releases.
Vulnerable Products
The following table lists Cisco products that are affected by the vulnerability that is described in this advisory. Customers should refer to the associated Cisco bug IDs for further details.
Affected Cisco Software Platform CVSS Base Score Security Impact Rating Cisco Bug ID First Fixed Release Secure Endpoint Connector for Linux CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Medium CSCwr70252 1.28.1 Secure Endpoint Connector for Mac CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Medium CSCwr70255 1.27.2 Secure Endpoint Connector for Windows CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Medium CSCwr70268 8.6.0 Secure Endpoint Private Cloud CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Medium CSCwr70257 4.2.7 or earlier with updated connectors Cisco products may be impacted differently depending on implementation and usage of ClamAV. For information on the effects of this vulnerability on specific Cisco products, see the Details 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:
- Secure Email Gateway
- Secure Web Appliance
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Impacts of ClamAV DoS Vulnerability on Affected Platforms
This vulnerability, which has a Medium Security Impact Rating (SIR), affects Linux, Mac, and Windows-based platforms. Exploitation of the vulnerability could cause the scanning process to crash, delaying or preventing further scanning operations. However, overall system stability is not affected. See the Security Risk Assessment section of the Cisco Security Vulnerability Policy for information about vulnerability scoring and SIRs.
Cisco Secure Endpoint Connector, which is distributed from Cisco Secure Endpoint Private Cloud, is affected by this vulnerability. Cisco Secure Endpoint Private Cloud is not affected.
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There are no workarounds that address this vulnerability.
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Cisco considers any workarounds and mitigations (if applicable) to be temporary solutions until an upgrade to a fixed software release is available. To fully remediate this vulnerability and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.
Fixed Releases
At the time of publication, the release information in the following table 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 platforms, and the right column lists the first software release that included the fix for this vulnerability.
Affected Cisco Software Platform First Fixed Release Secure Endpoint Connector for Linux 1.28.11 Secure Endpoint Connector for Mac 1.27.21 Secure Endpoint Connector for Windows 8.6.01 Secure Endpoint Private Cloud 4.2.7 or earlier with updated connectors2 1. Updated releases of Cisco Secure Endpoint Connector are available through the Cisco Secure Endpoint portal. Depending on the configured policy, Cisco Secure Endpoint Connector will automatically update.
2. Affected releases of Cisco Secure Endpoint Connector clients for Cisco Secure Endpoint Private Cloud have been updated in the connector repository. Customers will get these connector updates through normal content update processes.The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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This vulnerability was found during internal security testing.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial public release. - Final 2026-MAR-04
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SOFTWARE DOWNLOADS AND TECHNICAL SUPPORT
The Cisco Support and Downloads page on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool. Please note that customers may download only software that was procured from Cisco directly or through a Cisco authorized reseller or partner and for which the license is still valid.
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 Technical Assistance Center (TAC). 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.
When considering software upgrades, customers are advised to regularly consult the advisories for the relevant Cisco products 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.
LEGAL DISCLAIMER DETAILS
CISCO DOES NOT MAKE ANY EXPRESS OR IMPLIED GUARANTEES OR WARRANTIES OF ANY KIND, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. WITHOUT LIMITING THE GENERALITY OF THE FOREGOING, CISCO DOES NOT GUARANTEE THE ACCURACY OR COMPLETENESS OF THIS INFORMATION. THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
Copies or summaries of the information contained in this Security Advisory may lack important information or contain factual errors. Customers are advised to visit the Cisco Security Advisories page for the most recent version of this Security Advisory. The Cisco Product Security Incident Response Team (PSIRT) assesses only the affected and fixed release information that is documented in this advisory. See the Cisco Security Vulnerability Policy for more information.