Buffer overflow in Ffmpeg
CVE-2026-125250
FFmpeg through 9.0.2 contains a heap buffer overflow in the GIF encoder's gif_image_write_image() in libavcodec/gif.c because shrunk_buf is sized from the first frame's linesize. Attackers can supply PAL8 video whose frame linesize grows mid-stream, causing remap_frame_to_palette() to write past shrunk_buf and corrupt the heap during GIF transcoding.
Vulnerability class: Buffer Overflow
Published .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 (product)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/gif.c (technical-description)
- github.com/FFmpeg/FFmpeg/commit/26c2980980295e5516f308c5a2792d2a72e43eae (patch)
- www.vulncheck.com/advisories/ffmpeg-through-9.0.2-gif-encoder-heap-buffer-overf… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-125250?
- CVE-2026-125250 is a high-severity vulnerability in Ffmpeg, classified under Heap-based Buffer Overflow. CVSS score: 7.8/10. Published 2026-11-09.
- How severe is CVE-2026-125250?
- High severity. CVSS v3 base score is 7.8 out of 10.