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VulnerabilityPublished

CVE-2026-125103: FFmpeg · Use of Uninitialized Resource

Affects FFmpegSource CVE Database V5

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Not known to be exploited · CVSS 4.8 Medium.

Data as of 9 Nov 2026, 20:35 UTC

CVSS 4.0 base score
4.8Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.04.8
CNA (VulnCheck)CVSS 3.13.3
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/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

Until a fix is available, avoid processing untrusted MPEG-4 ALS files or use alternative software versions if possible.

Description

CVE-2026-125103 is an information disclosure vulnerability in FFmpeg versions up to 9.0.2. It occurs in the ff_mlz_decompression() function within libavcodec/mlz.c, where malformed MPEG-4 ALS files with out-of-range codes can cause uninitialized heap bytes to be copied into decoded audio output. This can lead to unintended disclosure of memory contents.

References

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