---
id: CVE-2026-120246
title: FFmpeg 4.4 through 9.0.2 Uninitialized Memory Disclosure via CDXL HAM Decoder
summary: >-
  FFmpeg 4.4 through 9.0.2 contains a use of uninitialized variable
  vulnerability in the CDXL decoder that leaks stack memory into decoded pixels
  via unfilled HAM palette entries. Attackers can craft a type-0 CDXL file whose
  HAM pixels sel…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-457
vendor: FFmpeg
product: FFmpeg
affected:
  - FFmpeg >= 4.4 <= 9.0.2
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T15:37:33.214014Z'
published: '2026-11-01'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T15:37:47.734Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-120246'
references:
  - url: 'https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24856'
  - url: >-
      https://github.com/FFmpeg/FFmpeg/commit/47313ad3f9f33b892384b976fb7c09b3c85fd74e
  - url: 'https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cdxl.c#L226-L229'
  - url: 'https://github.com/FFmpeg/FFmpeg'
  - url: >-
      https://www.vulncheck.com/advisories/ffmpeg-4.4-through-9.0.2-uninitialized-memory-disclosure-via-cdxl-ham-decoder
    label: >-
      VulnCheck Advisory: FFmpeg 4.4 through 9.0.2 Uninitialized Memory
      Disclosure via CDXL HAM Decoder
tags:
  - cve.org
epss: 0.00124
epssPercentile: 0.02128
ingestedAt: '2026-11-05T21:36:00.910Z'
---

## Overview

FFmpeg 4.4 through 9.0.2 contains a use of uninitialized variable vulnerability in the CDXL decoder that leaks stack memory into decoded pixels via unfilled HAM palette entries. Attackers can craft a type-0 CDXL file whose HAM pixels select unfilled new_palette entries in cdxl_decode_ham8() or cdxl_decode_ham6(), exposing stack bytes and pointer fragments in the BGR24 output.

## Affected

- `FFmpeg >= 4.4 <= 9.0.2`

## Remediation

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