Cisco Security Advisory
ClamAV Vulnerabilities Affecting Cisco Products: August 2026
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CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:X/RL:X/RC:X
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Multiple vulnerabilities in ClamAV could allow a remote attacker to cause a denial of service (DoS) condition, interrupting scanning operations.
For more information about these vulnerabilities, see the Details section of this advisory.
For additional information on these vulnerabilities in ClamAV, see the ClamAV blog.
Cisco has released software updates that address these vulnerabilities in affected Cisco platforms. There are no workarounds that address these vulnerabilities.
Notes:
- The Security Impact Rating (SIR) for these vulnerabilities is High for Windows-based platforms only because those platforms run the ClamAV scanning process in a privileged security context. The platforms that are highly impacted include Cisco Secure Endpoint Connector for Windows.
- The SIR for these vulnerabilities is Medium on other platforms, including Linux and Mac platforms, because those platforms run the ClamAV scanning process in a lower-privileged security context. The affected platforms include Secure Endpoint Connector for Linux and Mac.
- Cisco Secure Endpoint Private Cloud itself is not impacted by these vulnerabilities. However, the Cisco Secure Endpoint Connector software that is distributed from the device is impacted.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-WuuvVd26
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Vulnerable Products
The following table lists Cisco products that are affected by the vulnerabilities that are 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 IDs First Fixed Release Secure Endpoint Connector for Linux 5.3 Medium CSCwv87285 1.29.2 Secure Endpoint Connector for Mac 5.3 Medium CSCwv87286 1.27.4 Secure Endpoint Connector for Windows 7.5 High CSCwv87283 8.6.3
7.5.24.21780Secure Endpoint Private Cloud is not affected by these vulnerabilities. However, customers must push the fixed software from the cloud to their endpoints. Secure Endpoint Private Cloud releases 4.2.8 and later will support the fixed software for endpoints when it is released and made available as a connector software update. See Cisco bug ID CSCwv91588 for details.
Cisco products may be impacted differently depending on implementation and usage of ClamAV. For information on the effects of these vulnerabilities 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 these vulnerabilities.
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The vulnerabilities are not dependent on one another. Exploitation of one of the vulnerabilities is not required to exploit another vulnerability. In addition, a software release that is affected by one of the vulnerabilities may not be affected by the other vulnerabilities.
Details about the vulnerabilities are as follows:
CVE-2026-20337: ClamAV Zip File Format Processing Out-of-Bounds Write Vulnerability
A vulnerability in the zip archive parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device.
This vulnerability is due to improper boundary checks for content in zip files during scanning, which may result in an out-of-bounds write condition. An attacker could exploit this vulnerability by submitting a crafted zip file for scanning. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu34288
CVE ID: CVE-2026-20337
Security Impact Rating (SIR): High
CVSS Base Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-20338: ClamAV Zip File Format Processing Memory Corruption Vulnerability
A vulnerability in the zip archive parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device.
This vulnerability is due to improper memory handling when processing content in zip files during scanning. An attacker could exploit this vulnerability by submitting a crafted zip file for scanning. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate as a result of a memory double-free, resulting in a DoS condition on the affected software.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwv57797
CVE ID: CVE-2026-20338
Security Impact Rating (SIR): High
CVSS Base Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-20339: ClamAV PESpin File Format Processing Integer Overflow Vulnerability
A vulnerability in the PESpin file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts as a result of memory corruption on an affected device.
This vulnerability is due to improper boundary checks for content in PESpin files during scanning, which may result in an integer overflow. An attacker could exploit this vulnerability by submitting a crafted file that contains PESpin content to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu78432
CVE ID: CVE-2026-20339
Security Impact Rating (SIR): High
CVSS Base Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-20345: ClamAV GPT File Format Processing Memory Corruption Vulnerability
A vulnerability in the GPT file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts as a result of memory corruption on an affected device.
This vulnerability is due to improper handling of an endian conversion operation, which may result in an out-of-bounds buffer write. An attacker could exploit this vulnerability by submitting a crafted GPT file to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu59475
CVE ID: CVE-2026-20345
Security Impact Rating (SIR): High
CVSS Base Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-20346: ClamAV PDF File Format Processing Memory Corruption Vulnerability
A vulnerability in the PDF file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts as a result of memory corruption on an affected device.
This vulnerability is due to improper boundary checks for content in PDF files during scanning, which may result in an out-of-bounds buffer read. An attacker could exploit this vulnerability by submitting a crafted PDF file to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu65985
CVE ID: CVE-2026-20346
Security Impact Rating (SIR): High
CVSS Base Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-20347: ClamAV Mach-O File Format Processing Memory Corruption Vulnerability
A vulnerability in the Mach-O file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts as a result of memory corruption on an affected device.
This vulnerability is due to improper boundary checks for content in Mach-O files during scanning, which may result in an out-of-bounds buffer read. An attacker could exploit this vulnerability by submitting a crafted Mach-O file to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu65985
CVE ID: CVE-2026-20347
Security Impact Rating (SIR): High
CVSS Base Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-20348: ClamAV XAR File Format Processing Memory Corruption Vulnerability
A vulnerability in the XAR file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts as a result of memory corruption on an affected device.
This vulnerability is due to improper boundary checks for content in XAR files during scanning. An attacker could exploit this vulnerability by submitting a crafted file that contains XAR content to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to cause the ClamAV scanning process to terminate, resulting in a DoS condition on the affected software.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Bug ID(s): CSCwu99410
CVE ID: CVE-2026-20348
Security Impact Rating (SIR): High
CVSS Base Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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There are no workarounds that address these vulnerabilities.
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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 these vulnerabilities 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
Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table:
Cisco Product Cisco Bug ID First Fixed Release Secure Endpoint Connector for Linux CSCwv87285 1.29.21 Secure Endpoint Connector for Mac CSCwv87286 1.27.41 Secure Endpoint Connector for Windows CSCwv87283 8.6.31
7.5.24.217801Secure Endpoint Private Cloud CSCwv91588 Release no. TBD (Aug 2026)2 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 will be updated in the connector repository of Cisco Secure Endpoint Private Cloud after client releases become available. 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 aware that proof-of-concept exploit code is available for the vulnerabilities that are described in CVE-2026-20337 and CVE-2026-20338.
The Cisco PSIRT is not aware of proof-of-concept exploit code for any of the other vulnerabilities that are described in this advisory.
The Cisco PSIRT is not aware of any malicious use of the vulnerabilities that are described in this advisory.
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Cisco would like to thank the following researchers for reporting these vulnerabilities:
- Atuin - Automated Vulnerability Discovery Engine, Tianchu Chen of Tencent Xuanwu Lab: CVE-2026-20345
- Daggolu Rakesh: CVE-2026-20338
- Feng Xue: CVE-2026-20339
- Kevin Stubbings of GitHub: CVE-2026-20337
- leduckhuong: CVE-2026-20348
- Tristan Madani from Talence Security: CVE-2026-20346 and CVE-2026-20347
- Yazdan Soltani: CVE-2026-20338 and CVE-2026-20339
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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.
For additional information on Cisco's vulnerability management, disclosure cadence, and software patching strategy, see Cisco's Transition to a Risk-Based Vulnerability Disclosure Model.
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Show LessVersion Description Section Status Date 1.2 Added fix information for Cisco Secure Endpoint Connector. Summary, Vulnerable Products, and Fixed Releases Interim 2026-AUG-13 1.1 Clarified fix availability for Cisco Secure Endpoint Private Cloud. Vulnerable Products and Fixed Releases Interim 2026-AUG-10 1.0 Initial public release. - Interim 2026-AUG-07
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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.
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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.