Vulnerability · Published Nov 1, 2026 · Assigned by VulnCheck

CVE-2026-120246FFmpeg 4.4 through 9.0.2 Uninitialized Memory Disclosure via CDXL HAM Decoder

Medium 5.5

In plain English

A medium-severity security flaw in FFmpeg from FFmpeg. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).

Severity (CVSS 3.1)5.5Medium

Exploit odds (30 days)0.1%top 97.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	ffmpeg	no fix listed	DEBIAN-CVE-2026-120246
Debian:13	ffmpeg	no fix listed	DEBIAN-CVE-2026-120246
Debian:14	ffmpeg	no fix listed	DEBIAN-CVE-2026-120246
Ubuntu:26.10	ffmpeg	no fix listed	UBUNTU-CVE-2026-120246

Affected products (as reported)

Vendor	Product	Versions
FFmpeg	FFmpeg	4.4 – through 9.0.2

Weakness: CWE-457 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

References

https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24856 issue-tracking
https://github.com/FFmpeg/FFmpeg/commit/47313ad3f9f33b892384b976fb7c09b3c85fd74e patch
https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cdxl.c#L226-L229 technical-description
https://github.com/FFmpeg/FFmpeg product
VulnCheck Advisory: FFmpeg 4.4 through 9.0.2 Uninitialized Memory Disclosure via CDXL HAM Decoder third-party-advisory