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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| FFmpeg | FFmpeg | 4.4 – ≤ 9.0.2 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | ffmpeg | No fix yet | — |
| Debian 13 | ffmpeg | No fix yet | — |
| Debian 12 | ffmpeg | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | ffmpeg | No fix yet | — |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | ffmpeg | No fix yet | — |
| Ubuntu Pro 24.04 LTS | ffmpeg | No fix yet | — |
| Ubuntu Pro 22.04 LTS | ffmpeg | No fix yet | — |
| Ubuntu Pro 20.04 LTS | ffmpeg | No fix yet | — |
| Ubuntu Pro 18.04 LTS | ffmpeg | No fix yet | — |
| Ubuntu Pro 16.04 LTS | ffmpeg | No fix yet | — |
| Ubuntu Pro 14.04 LTS | libav | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | ffmpeg-7 +4 | No fix yet | — |
Advisories 1
- WID-SEC-2026-4282 ffmpeg: Mehrere Schwachstellen ermöglichen Offenlegung von Informationen BSI CERT-Bund (WID) · Nov 1, 2026
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