CVE-2026-20243

ClamAV ALZ Archive Processing Denial of Service Vulnerability

HIGH

7.5

CVSS Score

Published: July 1, 2026 at 04:30 PM UTC

Updated: October 25, 2026 at 05:10 PM UTC

2 products affected across 2 vendorsClamAVSecure Endpoint

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Severity

HIGH7.5

Exploit prediction

EPSS 0.6%

SSVC

No known exploit

Description

A vulnerability in the ALZ file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition, or possibly other expanded impacts, resulting from memory corruption on an affected device. This vulnerability is due to improper boundary checks for content in ALZ files during scanning, which may result in an out-of-bounds buffer write. An attacker could exploit this vulnerability by submitting a crafted file that contains ALZ 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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Secure Endpoint · Cisco

95%

v < 1.27.2v < 1.29.0v < 8.6.21.10.0 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 1.6.0 1.7.0 1.8.0 1.8.1 1.8.4 1.9.0 1.9.1 6.0.7 6.0.9 6.1.5 6.1.7 6.1.9 6.2.1 6.2.19 6.2.3 6.2.5 6.2.9 6.3.1 6.3.3 6.3.5 6.3.7 7.0.5 7.1.1 7.1.5 7.2.11 7.2.13 7.2.3 7.2.5 7.2.7 7.3.1 7.3.13 7.3.15 7.3.3 7.3.5 7.3.9 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 7.5.11 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 7.5.3 7.5.5 7.5.7 7.5.9 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

Affected range stops below 1.27.2, so it looks safe — our inference, not a vendor statement

Affected range stops below 1.29.0, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.6.2, so it looks safe — our inference, not a vendor statement

ClamAV · Clamav

95%

1.4.0 ≤ v < 1.4.51.5.0 ≤ v < 1.5.3

Affected range stops below 1.4.5, so it looks safe — our inference, not a vendor statement

Affected range stops below 1.5.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-88cFYyxR

References (1)

Vendor Advisory

Source: cverecord

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-88cFYyxR

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHcisco

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-120

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