FFmpeg through 9.0.2 Double Free via cbs_sei_delete_message in cbs_sei.c

Advisories

FFmpeg through 9.0.2 Double Free via cbs_sei_delete_message in cbs_sei.c

Severity: high
Date: 11/9/2026
Affecting: FFmpeg <= 9.0.2
CVE: CVE-2026-125269
CWE: CWE-415 Double Free
CVSS: 7.3
CVSS V4 Vector: CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
References: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25020
Patch Commit
https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cbs_sei.c#L287
https://github.com/FFmpeg/FFmpeg
Credit: Claude and Ada Logics, Joshua Rogers (AISLE Research), Michael Niedermayer
Description: 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.

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