---
id: CVE-2026-125187
title: FFmpeg through 9.0.2 TTA Encoder Reachable Assertion via tta_encode_frame()
summary: >-
  FFmpeg through 9.0.2 contains a reachable assertion vulnerability in the TTA
  encoder's tta_encode_frame() in libavcodec/ttaenc.c, which never reserves
  output packet space for the 4-byte CRC. Attackers can supply audio whose
  sample values…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-617
vendor: FFmpeg
product: FFmpeg
affected:
  - FFmpeg <= 9.0.2
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-09T21:02:28.982674Z'
published: '2026-11-09'
updated: '2026-11-09'
sourceUpdated: '2026-11-09T21:06:57.465Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-125187'
references:
  - url: 'https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25694'
  - url: >-
      https://github.com/FFmpeg/FFmpeg/commit/29a629e788c4343ff2e923095b8f38769fe2e470
    label: Patch Commit
  - url: 'https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/ttaenc.c#L93'
  - url: 'https://github.com/FFmpeg/FFmpeg'
  - url: >-
      https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-tta-encoder-reachable-assertion-via-tta-encode-frame
    label: >-
      VulnCheck Advisory: FFmpeg through 9.0.2 TTA Encoder Reachable Assertion
      via tta_encode_frame()
tags:
  - cve.org
ingestedAt: '2026-11-09T19:18:02.608Z'
---

## Overview

FFmpeg through 9.0.2 contains a reachable assertion vulnerability in the TTA encoder's tta_encode_frame() in libavcodec/ttaenc.c, which never reserves output packet space for the 4-byte CRC. Attackers can supply audio whose sample values and length produce a small, poorly compressible final frame, triggering the av_assert0() in flush_put_bits() and aborting applications transcoding to TTA.

## Affected

- `FFmpeg <= 9.0.2`

## Remediation

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