Use After Free in Ffmpeg
CVE-2026-125255
FFmpeg through 9.0.2 contains a use after free vulnerability in libavcodec/mjpegdec.c that allows attackers to trigger freed buffer reads by sending a SOF marker without a preceding SOI. Attackers can supply crafted MJPEG streams causing ff_mjpeg_decode_sof() to pass a stale raw_image_buffer pointer to hwaccel decoders like NVDEC, crashing applications or leaking heap contents.
Vulnerability class: Use-After-Free
Published .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:L/AC:H/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/25231 (issue-tracking)
- github.com/FFmpeg/FFmpeg/commit/f58a6776546567367baf5223df9ffbfd289299f8 (patch)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/mjpegdec.c (technical-description)
- github.com/FFmpeg/FFmpeg (product)
- www.vulncheck.com/advisories/ffmpeg-through-9.0.2-use-after-free-in-mjpeg-hardw… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-125255?
- CVE-2026-125255 is a medium-severity vulnerability in Ffmpeg, classified under Use After Free. CVSS score: 5.3/10. Published 2026-11-09.
- How severe is CVE-2026-125255?
- Medium severity. CVSS v3 base score is 5.3 out of 10.