---
id: CVE-2026-75146
title: FFmpeg Out-of-Bounds Read in DASH Demuxer via dashdec.c
summary: >-
  FFmpeg before commit 65b0dab contains an out-of-bounds read in the DASH
  demuxer (libavformat/dashdec.c). When a live DASH manifest is refreshed with a
  startNumber that is lower than the previous value, the current sequence number
  is driv…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-125
vendor: FFmpeg
product: FFmpeg
affected:
  - FFmpeg < 65b0dab903e5975e036b30ecc58f5935d4f151e0
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-08-20T14:55:54.873673Z'
published: '2026-08-19'
updated: '2026-10-27'
sourceUpdated: '2026-10-27T10:14:32.933Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-75146'
references:
  - url: 'https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24093'
    label: Pull Request
  - url: >-
      https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/65b0dab903e5975e036b30ecc58f5935d4f151e0
    label: Patch Commit
  - url: >-
      https://www.vulncheck.com/advisories/ffmpeg-out-of-bounds-read-in-dash-demuxer-via-dashdec-c
tags:
  - cve.org
epss: 0.00261
epssPercentile: 0.1784
ingestedAt: '2026-10-27T16:11:59.272Z'
---

## Overview

FFmpeg before commit 65b0dab contains an out-of-bounds read in the DASH demuxer (libavformat/dashdec.c). When a live DASH manifest is refreshed with a startNumber that is lower than the previous value, the current sequence number is driven negative. The fragment retrieval function checked only the upper bound before indexing the fragments array, allowing a negative index to be used and causing an out-of-bounds read. A malicious or misconfigured DASH server can trigger this by serving a live manifest with a decreasing startNumber across a manifest refresh.

## Affected

- `FFmpeg < 65b0dab903e5975e036b30ecc58f5935d4f151e0`

## Remediation

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