CVE-2026-125203: FFmpeg before 8.1.3 and 9.x before 9.0.2 Heap Buffer Overflow in Cook Multichannel Decoder
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.1%
EPSS score, percentile 3.5 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 8.5 High
CVSS v4.0 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
- Which versions are affected?
Affected
- before 8.1.3
- from 9.0 to before 9.0.2
Source: CISA KEV 2026.11.10, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
Description
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.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.
Source: CVE List, as of . About the data.
What to do
Advisories and patches
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
Versions by product, as listed in the CVE record (1 product)
| Status | Versions |
|---|---|
| Affected | before 8.1.3 |
| Affected | from 9.0 to before 9.0.2 |
Versions not listed are: unaffected.
Source: CVE List, as of . About the data.
Weakness
CWE-787
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |