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CVE-2026-125203VulnerabilityPublished Updated

FFmpeg before 8.1.3 and 9.x before 9.0.2 contains a heap buffer overflow vulnerability in the Cook multichannel

Affects ffmpegSource GCVE Database

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Authoritative record:CVE-2026-125203· High 8.5

Not known to be exploited · CVSS 8.5 High · fixed in 8.1.3 : patch ffmpeg soon.

Data as of 12 Nov 2026, 20:54 UTC

CVSS 4.0 base score
8.5High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.08.5
CNA (VulnCheck)CVSS 3.17.8
CNACVSS 4.08.5
Patch
Available – fixed in 8.1.3
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/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 12 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10ffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=stonkingOther threatsAffected
  • =7:8.0.1-3ubuntu2
  • =7:8.1-3ubuntu3
  • =7:8.1.2-2ubuntu2
Fixed in–
Ubuntu Pro 26.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/resoluteOther threatsAffected
  • 7:7.1.1-1ubuntu4 – 7:8.0.1-3ubuntu2+esm5
11 affected builds
Fixed in–
Ubuntu Pro 24.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/nobleOther threatsAffected
  • 7:6.0-6ubuntu1 – 7:6.1.1-3ubuntu5+esm15
22 affected builds
Fixed in–
Ubuntu Pro 22.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/jammyOther threatsAffected
  • 7:4.4-6ubuntu5 – 7:4.4.2-0ubuntu0.22.04.1+esm17
24 affected builds
Fixed in–
Ubuntu Pro 20.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/focalOther threatsAffected
  • 7:4.1.4-1build2 – 7:4.2.7-0ubuntu0.1+esm18
26 affected builds
Fixed in–
Ubuntu Pro 18.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/bionicOther threatsAffected
  • 7:3.3.4-2 – 7:3.4.11-0ubuntu0.1+esm16
30 affected builds
Fixed in–

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

AI-suggested

A fix is available in FFmpeg versions 8.1.3 and 9.0.2 and later. Users and administrators should upgrade to these or newer versions to remediate the vulnerability. No additional mitigations are specified.

Description

FFmpeg versions before 8.1.3 and 9.x before 9.0.2 contain a heap buffer overflow vulnerability in the Cook multichannel decoder. This flaw occurs because the decoder does not verify that subpacket channel masks are disjoint, allowing crafted RealMedia Cook streams with overlapping masks to cause out-of-bounds writes during decoding.

References

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