CVE-2026-75145

FFmpeg before commit b4c199c contains an incorrect integer narrowing conversion in the AV1 RTP packetizer (libavformat/rtpenc_av1.c). The OBU size is cast to long before comparison against the remaining frame size. On targets where long is 32 bits, including 64-bit Windows, sufficiently large OBU size values are sign-flipped by the narrowing cast, producing a negative value that passes the payload size check. This allows an oversized OBU to bypass the safety bound on affected platforms, leading to out-of-bounds memory access when the oversized value is subsequently used as a copy length.

Score

CVSS 4.0 5.8 Medium

Status

Awaiting Analysis - disclosure@vulncheck.com

Published

2026-08-19

Last modified

2026-10-27

Weaknesses

CWE-681

Affected products

• Ffmpeg (Ffmpeg)

References

• https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/b4c199c5906ff53368926c2a5839881f41957e7f
• https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24090
• https://www.vulncheck.com/advisories/ffmpeg-integer-narrowing-conversion-oob-memory-access-in-av1-rtp-packetizer