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VulnerabilityPublished

CVE-2026-125197: FFmpeg · Integer Underflow

Affects FFmpegSource CVE Database V5

0
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Not known to be exploited · CVSS 6.9 Medium.

Data as of 9 Nov 2026, 20:33 UTC

CVSS 4.0 base score
6.9Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.06.9
CNA (VulnCheck)CVSS 3.16.1
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 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 9 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
FFmpegFFmpegAffected
  • <=9.0.2
Fixed in–
GitHubFFmpegpkg:github/FFmpegOther threatsAffected
  • <=9.0.2
Fixed in–

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

AI-suggested

Users should check the vendor advisory for current remediation guidance. Until a fix is available, avoid processing untrusted AVI or MKV files containing LCL video streams with short packets and the FLAG_MULTITHREAD flag.

Description

CVE-2026-125197 is an integer underflow vulnerability in FFmpeg up to version 9.0.2. It occurs in the decode_frame() function of libavcodec/lcldec.c and allows attackers to cause a heap out-of-bounds read by supplying crafted short ZLIB packets with the FLAG_MULTITHREAD flag. This can be triggered by a malicious AVI or MKV file containing an LCL video stream with packets shorter than 8 bytes, bypassing length clamping and potentially crashing the decoding application.

References

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