Vulnerability · Published Nov 1, 2026 · Assigned by VulnCheck
CVE-2026-120251imagecodecs 2026.3.6 through 2026.10.10 Infinite Loop via ccittfax4_decode()
Medium 5.5
In plain English
A medium-severity infinite loop in imagecodecs from cgohlke. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).
Severity (CVSS 3.1)5.5Medium
Exploit odds (30 days)0.1%top 97.9% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known
Official description
imagecodecs 2026.3.6 through 2026.10.10 contains an infinite loop vulnerability in ccitt_fax4_decode_size() that allows attackers to hang the calling process by supplying a crafted CCITT Group 4 stream. Attackers can provide an 8-byte G4 stream lacking EOFB to ccittfax4_decode() or the numcodecs Ccittfax4 codec, consuming full CPU until the process is killed.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| cgohlke | imagecodecs | 2026.3.6 – through 2026.10.10 |
Weakness: CWE-835 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
References
- GitHub Issue #158 issue-tracking
- https://github.com/cgohlke/imagecodecs/blob/v2026.10.10/3rdparty/ccitt/ccitt.c#L1449 technical-description
- https://github.com/cgohlke/imagecodecs product
- VulnCheck Advisory: imagecodecs 2026.3.6 through 2026.10.10 Infinite Loop via ccittfax4_decode() third-party-advisory