---
id: CVE-2026-75145
title: FFmpeg Integer Narrowing Conversion OOB Memory Access in AV1 RTP Packetizer
summary: >-
  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 …
severity: medium
cvss: 5.8
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:H'
cvssSource: cna
cwe:
  - CWE-681
vendor: FFmpeg
product: FFmpeg
affected:
  - FFmpeg < b4c199c5906ff53368926c2a5839881f41957e7f
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-08-21T19:52:00.435341Z'
published: '2026-08-19'
updated: '2026-10-27'
sourceUpdated: '2026-10-27T10:14:32.244Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-75145'
references:
  - url: 'https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24090'
    label: Pull Request
  - url: >-
      https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/b4c199c5906ff53368926c2a5839881f41957e7f
    label: Patch Commit
  - url: >-
      https://www.vulncheck.com/advisories/ffmpeg-integer-narrowing-conversion-oob-memory-access-in-av1-rtp-packetizer
tags:
  - cve.org
epss: 0.00158
epssPercentile: 0.04946
ingestedAt: '2026-10-27T16:11:59.275Z'
---

## Overview

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.

## Affected

- `FFmpeg < b4c199c5906ff53368926c2a5839881f41957e7f`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.