FFmpeg before 8.1.3 and 9.x before 9.0.2 Heap Buffer Overflow in Cook Multichannel Decoder
FFmpeg before 8.1.3 and 9.0 before 9.0.2 is affected when decoding Cook multichannel audio whose subpacket channel masks overlap. Fixed in 8.1.3 and 9.0.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 8.1.3, 9.0.2
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. FFmpeg versions before 8.1.3 and 9.x before 9.0.2 (the affected range is FFmpeg before 8.1.3 and 9.0 before 9.0.2) The Cook multichannel decoder in libavcodec/cook.c is used on a stream whose subpacket channel masks overlap, because the decoder does not verify that they are disjoint
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 14/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
FFmpeg before 8.1.3 and 9.x before 9.0.2 contains a heap buffer overflow vulnerability in the Cook multichannel decoder in libavcodec/cook.c that fails to verify subpacket channel masks are disjoint. Attackers can supply a crafted RealMedia Cook stream with overlapping subpacket masks, causing cook_decode_frame() to write decoded samples beyond allocated output planes in any application decoding the file.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.5/10CVSS 8.5
- No patch0/5No signal
What would change the score
- Would score about 64 if added to CISA KEV
- Would score about 59 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
FFmpeg versions before 8.1.3 and 9.x before 9.0.2 (the affected range is FFmpeg before 8.1.3 and 9.0 before 9.0.2) The Cook multichannel decoder in libavcodec/cook.c is used on a stream whose subpacket channel masks overlap, because the decoder does not verify that they are disjointUpgrade to a fixed version: 8.1.3, 9.0.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- FFmpeg FFmpeg
fixed in 8.1.3; From 9.0 · fixed in 9.0.2
Evidence 5
- Patch
- Report
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-125203
Is CVE-2026-125203 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The Cook multichannel decoder does not check that subpacket channel masks are disjoint. A crafted file with overlapping masks can make cook_decode_frame() write decoded samples beyond the allocated output planes, a heap buffer overflow (CWE-787).Source: vulncheck.com
Which versions are affected by CVE-2026-125203?
FFmpeg: before 8.1.3; from 9.0 before 9.0.2.Source: cve.now feed data
Am I affected, and how do I check?
FFmpeg versions before 8.1.3 and 9.x versions before 9.0.2 are in the affected range. To check a build, run ffmpeg -version and compare the version number. The issue concerns decoding Cook multichannel streams whose subpacket channel masks overlap.Source: vulncheck.com
How do I fix CVE-2026-125203?
Upgrade to FFmpeg 8.1.3 or 9.0.2, or a later release. The facts list no workaround.Source: vulncheck.com