FFmpeg: Heap buffer overflow in dvbsub_encode (CVE-2026-125233)
FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in dvbsub_encode() in libavcodec/dvbsubenc.c due to undercounting CLUT segment headers.
CVE search metadata
CVE search record: CVE-2026-125233. Severity: high. CVSS: 7.8. KEV: no. Product: FFmpeg (<= 9.0.2). Brief: FFmpeg: Heap buffer overflow in dvbsub_encode (CVE-2026-125233). Brief link: https://feed.craftedsignal.io/briefs/2026-11-ffmpeg-dvbsub-overflow/
Triage facts
Revision 1- Applicability
- FFmpeg (<= 9.0.2)
- Evidence
- Unknown
- Severity
- High
- Sources
- 1 public source
- Freshness
- Revision 1Nov 9, 19:55 UTC
- Vulnerabilities
- 1 CVE
- Source quality
- A2Roughly even chance
FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in dvbsub_encode() in libavcodec/dvbsubenc.c. The vulnerability occurs because the code undercounts each CLUT segment header by two bytes.
Impact
Attackers can supply a file with many bitmap subtitle rectangles that, when transcoded to the dvbsub encoder, writes past the output buffer and corrupts heap memory.