CVE-2026-20243ClamAV ALZ Archive Processing Denial of Service Vulnerability
- 7.5HighCVSS base score
- 0.57%Exploitation in 30 daysEPSS · top 52% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By cisco
- 9 months later
· 9 months later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| ciscoCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Analyzed | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.57% · top 52% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
- affected 7.0.5
- affected 6.2.19
- affected 7.3.3
- affected 7.2.13
- affected 6.1.5
- affected 6.3.1
- affected 6.2.5
- affected 7.3.5
- affected 6.2.1
- affected 7.2.7
- affected 7.1.1
- affected 6.3.5
- affected 6.2.9
- affected 7.3.1
- affected 6.1.7
- affected 7.2.11
- affected 7.2.3
- affected 7.1.5
- affected 6.3.3
- affected 7.3.9
- affected 6.2.3
- affected 6.1.9
- affected 6.0.9
- affected 7.2.5
- affected 6.0.7
- affected 6.3.7
- affected 1.12.3
- affected 1.8.0
- affected 1.11.1
- affected 1.12.4
- affected 1.10.0
- affected 1.12.0
- affected 1.8.1
- affected 1.10.1
- affected 1.12.1
- affected 1.12.6
- affected 1.14.0
- affected 1.10.2
- affected 1.12.7
- affected 1.12.2
- and 106 more
What to do
Exploitation: The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.
References
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-41086 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-20243)Record last updated .