Double Free in Ffmpeg
CVE-2026-125269
FFmpeg through 9.0.2 contains a double free vulnerability in libavcodec/cbs_sei.c where cbs_sei_delete_message() leaves a stale extension_data reference that ff_cbs_sei_add_message() reuses. Attackers can supply a crafted H.264 stream with a display orientation SEI message followed by payload extension data, processed by h264_metadata with display_orientation=insert, to corrupt heap memory.
Vulnerability class: Double Free
Published .
CVSS v3 metric
CVSS v3 base score 7.0 (High). Vector: CVSS:3.1/AV:L/AC:H/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/25020 (issue-tracking)
- github.com/FFmpeg/FFmpeg/commit/2c515eea07df719379e7f73deeeb7ccb8768433f (patch)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cbs_sei.c (technical-description)
- github.com/FFmpeg/FFmpeg (product)
- www.vulncheck.com/advisories/ffmpeg-through-9.0.2-double-free-via-cbs-sei-delet… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-125269?
- CVE-2026-125269 is a high-severity vulnerability in Ffmpeg, classified under Double Free. CVSS score: 7.0/10. Published 2026-11-09.
- How severe is CVE-2026-125269?
- High severity. CVSS v3 base score is 7.0 out of 10.