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CVE-2026-120251VulnerabilityPublished

imagecodecs 2026.3.6 through 2026.10.10 contains an infinite loop vulnerability in ccitt_fax4_decode_size() that

Affects imagecodecsSource GCVE Database

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Authoritative record:CVE-2026-120251· Medium 6.8

Not known to be exploited · CVSS 6.8 Medium.

Data as of 1 Nov 2026, 04:22 UTC

CVSS 4.0 base score
6.8Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.06.8
CNA (VulnCheck)CVSS 3.15.5
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
PyPIimagecodecspkg:pypi/imagecodecsOther threatsAffected
  • >=2026.3.6 <=2026.10.10
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is available, avoid processing untrusted CCITT Group 4 streams or implement input validation to detect malformed streams lacking EOFB.

Description

An infinite loop vulnerability exists in imagecodecs versions 2026.3.6 through 2026.10.10 within the ccitt_fax4_decode_size() function. This flaw allows attackers to cause a denial-of-service by supplying a crafted CCITT Group 4 stream that lacks an End Of Facsimile Block (EOFB), leading to full CPU consumption until the affected process is terminated.

References

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