FFmpeg: Heap buffer overflow in Cook multichannel decoder (CVE-2026-125203)
A heap buffer overflow in the FFmpeg Cook multichannel decoder allows an out-of-bounds write via a crafted RealMedia stream.
CVE search metadata
CVE search record: CVE-2026-125203. Severity: high. CVSS: 7.8. KEV: no. Product: FFmpeg (< 8.1.3), FFmpeg (9.x < 9.0.2). Brief: FFmpeg: Heap buffer overflow in Cook multichannel decoder (CVE-2026-125203). Brief link: https://feed.craftedsignal.io/briefs/2026-11-ffmpeg-heap-overflow-a2833aa1/
Triage facts
Revision 1- Applicability
- FFmpeg (< 8.1.3), FFmpeg (9.x < 9.0.2)
- Evidence
- Unknown
- Severity
- High
- Sources
- 1 public source
- Freshness
- Revision 1Nov 9, 19:52 UTC
- Vulnerabilities
- 1 CVE
- Source quality
- A2Roughly even chance
FFmpeg versions before 8.1.3 and 9.x before 9.0.2 contain a heap buffer overflow vulnerability in the Cook multichannel decoder located in 'libavcodec/cook.c'. The vulnerability occurs because the decoder fails to verify that subpacket channel masks are disjoint. An attacker can supply a crafted RealMedia Cook stream with overlapping subpacket masks, causing the 'cook_decode_frame()' function to write decoded samples beyond allocated output planes in any application decoding the file.