CVE-2026-75145 (CVSS 5.8)

Description

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.

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CVSS v3.1 Score

5.8

MEDIUM

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

EPSS — Exploit Prediction

0.0012

Probability of exploitation

0.02%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-681 CWE-681

References

Other 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

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 5.8 (MEDIUM).

How severe is CVE-2026-75145? +

CVE-2026-75145 has a CVSS v3.1 score of 5.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0012, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-75145? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-75145