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.

CVSS 4.0

5.8CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

5.8CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:H

EPSS

0.2% chance of exploitation in the next 30 days; higher than 4% of CVEs (scores of 2026-10-25)

CWE

CWE-681

Published

2026-08-19

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

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

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