Vulnerability in Ffmpeg
CVE-2026-120246
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.
Published .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24856 (issue-tracking)
- github.com/FFmpeg/FFmpeg/commit/47313ad3f9f33b892384b976fb7c09b3c85fd74e (patch)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cdxl.c (technical-description)
- github.com/FFmpeg/FFmpeg (product)
- www.vulncheck.com/advisories/ffmpeg-4.4-through-9.0.2-uninitialized-memory-disc… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-120246?
- CVE-2026-120246 is a medium-severity vulnerability in Ffmpeg, classified under CWE-457. CVSS score: 5.5/10. Published 2026-11-01.
- How severe is CVE-2026-120246?
- Medium severity. CVSS v3 base score is 5.5 out of 10.