Cisco ClamAV up to 8.4.5.30483 Zip Archive Parser double free

Summaryinfo

A vulnerability classified as critical has been found in Cisco ClamAV. This affects an unknown function of the component Zip Archive Parser. This manipulation causes double free. This vulnerability appears as CVE-2026-20338. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Cisco ClamAV. It has been declared as critical. Affected by this vulnerability is some unknown processing of the component Zip Archive Parser. The manipulation with an unknown input leads to a double free vulnerability. The CWE definition for the vulnerability is CWE-415. The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations. As an impact it is known to affect availability. The summary by CVE is:

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.

It is possible to read the advisory at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2026-20338 since 10/08/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/07/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Anti-Malware Software

Vendor

• Cisco

Name

• ClamAV

Version

• 1.6.0
• 1.7.0
• 1.8.0
• 1.8.1
• 1.8.4
• 1.9.0
• 1.9.1
• 1.10.0
• 1.10.1
• 1.10.2
• 1.11.0
• 1.11.1
• 1.12.0
• 1.12.1
• 1.12.2
• 1.12.3
• 1.12.4
• 1.12.5
• 1.12.6
• 1.12.7
• 1.13.0
• 1.13.1
• 1.13.2
• 1.14.0
• 1.14.1
• 1.15.0
• 1.15.1
• 1.15.2
• 1.15.3
• 1.15.4
• 1.15.5
• 1.15.6
• 1.16.0
• 1.16.1
• 1.16.2
• 1.16.3
• 1.17.0
• 1.17.1
• 1.17.2
• 1.18.0
• 1.18.1
• 1.19.0
• 1.20.0
• 1.20.1
• 1.20.2
• 1.20.3
• 1.20.4
• 1.20.5
• 1.20.6
• 1.20.7
• 1.20.8
• 1.21.0
• 1.21.1
• 1.21.2
• 1.21.3
• 1.22.0
• 1.22.1
• 1.22.2
• 1.22.3
• 1.22.4
• 1.23.0
• 1.23.1
• 1.24.0
• 1.24.1
• 1.24.2
• 1.24.3
• 1.24.4
• 1.24.5
• 1.25.0
• 1.25.1
• 1.25.2
• 1.26.0
• 1.26.1
• 1.27.0
• 1.27.1
• 1.27.2
• 6.0.7
• 6.0.9
• 6.1.5
• 6.1.7
• 6.1.9
• 6.2.1
• 6.2.3
• 6.2.5
• 6.2.9
• 6.2.19
• 6.3.1
• 6.3.3
• 6.3.5
• 6.3.7
• 7.0.5
• 7.1.1
• 7.1.5
• 7.2.3
• 7.2.5
• 7.2.7
• 7.2.11
• 7.2.13
• 7.3.1
• 7.3.3
• 7.3.5
• 7.3.9
• 7.3.13
• 7.3.15
• 7.4.1
• 7.4.1.20425
• 7.4.1.20439
• 7.4.3
• 7.4.3.20679
• 7.4.5
• 7.5.1.20813
• 7.5.1.20833
• 7.5.3
• 7.5.5
• 7.5.7
• 7.5.9
• 7.5.11
• 7.5.13.21586
• 7.5.13.21598
• 7.5.15.21611
• 7.5.17.21680
• 7.5.19
• 7.5.20
• 7.5.21.21732
• 8.0.1.21160
• 8.0.1.21164
• 8.1.3
• 8.1.3.21242
• 8.1.5
• 8.1.5.21322
• 8.1.7
• 8.1.7.21417
• 8.1.7.21512
• 8.1.7.21585
• 8.2.1.21612
• 8.2.1.21650
• 8.2.3.30119
• 8.2.4.30130
• 8.4.0
• 8.4.1.30298
• 8.4.1.30307
• 8.4.2.30317
• 8.4.3
• 8.4.4.30419
• 8.4.4.30467
• 8.4.5.30483

License

• free

Website

• Vendor: https://www.cisco.com/

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