---
id: CVE-2026-125098
title: FFmpeg through 9.0.2 WebP Decoder Information Disclosure via Short ALPH Chunk
summary: >-
  FFmpeg through 9.0.2 contains an information disclosure vulnerability in
  vp8_lossy_decode_alpha() in libavcodec/webp.c that leaves alpha plane memory
  uninitialized for short uncompressed ALPH chunks. Attackers can supply a
  crafted WebP i…
severity: low
cvss: 3.3
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-908
vendor: FFmpeg
product: FFmpeg
affected:
  - FFmpeg <= 9.0.2
published: '2026-11-09'
updated: '2026-11-09'
sourceUpdated: '2026-11-09T19:10:54.228Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-125098'
references:
  - url: 'https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25715'
  - url: >-
      https://github.com/FFmpeg/FFmpeg/commit/92b318e0b33623720d9f128ad7bc5fa8277c34f7
    label: Patch Commit
  - url: 'https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/webp.c#L1257'
  - url: 'https://github.com/FFmpeg/FFmpeg'
  - url: >-
      https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-webp-decoder-information-disclosure-via-short-alph-chunk
    label: >-
      VulnCheck Advisory: FFmpeg through 9.0.2 WebP Decoder Information
      Disclosure via Short ALPH Chunk
tags:
  - cve.org
ingestedAt: '2026-11-09T19:18:02.626Z'
---

## Overview

FFmpeg through 9.0.2 contains an information disclosure vulnerability in vp8_lossy_decode_alpha() in libavcodec/webp.c that leaves alpha plane memory uninitialized for short uncompressed ALPH chunks. Attackers can supply a crafted WebP image whose ALPH chunk is shorter than width * height to disclose stale pixel data from previously decoded frames.

## Affected

- `FFmpeg <= 9.0.2`

## Remediation

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