Vulnerability in Cgohlke Imagecodecs
CVE-2026-120251
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.
Published .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/cgohlke/imagecodecs/issues/158 (issue-tracking)
- github.com/cgohlke/imagecodecs/blob/v2026.10.10/3rdparty/ccitt/ccitt.c (technical-description)
- github.com/cgohlke/imagecodecs (product)
- www.vulncheck.com/advisories/imagecodecs-2026.3.6-through-2026.10.10-infinite-l… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-120251?
- CVE-2026-120251 is a medium-severity vulnerability in Cgohlke Imagecodecs, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.5/10. Published 2026-11-01.
- How severe is CVE-2026-120251?
- Medium severity. CVSS v3 base score is 5.5 out of 10.