CVE-2026-120251 (CVSS 5.5)

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.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-835 CWE-835

References

Other References

https://github.com/cgohlke/imagecodecs https://github.com/cgohlke/imagecodecs/blob/v2026.10.10/3rdparty/ccitt/ccitt.c#L1449 https://github.com/cgohlke/imagecodecs/issues/158 https://www.vulncheck.com/advisories/imagecodecs-2026.3.6-through-2026.10.10-infinite-loop-via-ccittfax4-decode

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-120251? +

CVE-2026-120251 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-120251? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-120251