Out-of-bounds Read in Ffmpeg
CVE-2026-125261
FFmpeg through 9.0.2 contains an out-of-bounds read vulnerability in the SGI encoder's encode_frame() in libavcodec/sgienc.c, where unsigned size variables mis-handle negative linesize frames. Attackers can supply a video whose display matrix triggers autorotate vflip, so transcoding to SGI images reads pixel data far outside the frame and crashes the process.
Vulnerability class: Buffer Overflow
Published .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25690 (issue-tracking)
- github.com/FFmpeg/FFmpeg/commit/c6e5b6105aa13f6b0df2a646da608078cfe52d79 (patch)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/sgienc.c (technical-description)
- github.com/FFmpeg/FFmpeg (product)
- www.vulncheck.com/advisories/ffmpeg-through-9.0.2-sgi-encoder-out-of-bounds-rea… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-125261?
- CVE-2026-125261 is a medium-severity vulnerability in Ffmpeg, classified under Out-of-bounds Read. CVSS score: 6.1/10. Published 2026-11-09.
- How severe is CVE-2026-125261?
- Medium severity. CVSS v3 base score is 6.1 out of 10.