FFmpeg 4.4 through 9.0.2 Uninitialized Memory Disclosure via CDXL HAM Decoder
Affects FFmpeg 4.4 through 9.0.2 when decoding CDXL HAM6 or HAM8 images with BGR24 output. The checked facts list no vendor rating or fixed version.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 12/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fix or patch referenced
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
FFmpeg, the widely used open-source multimedia framework, is affected in versions 4.4 through 9.0.2 when decoding Amiga CDXL video files. A specially crafted file can cause the decoder to leak uninitialized stack memory into the output images, potentially exposing sensitive memory contents such as pointer fragments.
Read the original 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.
What to do
Check whether your setup matches what the bug needs.
Affects the CDXL HAM decoding path, which is used when encoding is 1 and bpp is 6 or 8 (BGR24 output). Type-0 CDXL palette import leaves only part of the palette initialized (10 entries for HAM6, 42 for HAM8).Apply the patch listed under Evidence.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- FFmpeg FFmpeg
From 4.4 · through 9.0.2
Evidence 5
- Patch
- Report
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-120246
What does this mean?
When an FFmpeg CDXL HAM image uses Type-0 palette import, only some palette entries are set, leaving the rest uninitialized. Memory from those unfilled entries can then appear in the decoded pixel output.Source: github.com, code.ffmpeg.org
Am I affected, and how do I check?
Versions 4.4 through 9.0.2 are listed as affected. The bug is in the CDXL HAM decoding path, used when encoding is 1 and bpp is 6 or 8 (BGR24 output), and only Type-0 palette import leaves entries uninitialized. To check a setup, look at the FFmpeg version in use and whether it decodes CDXL HAM6 or HAM8 images.Source: github.com, code.ffmpeg.org
What should I do about it?
The checked facts do not name a fixed version or a workaround, so no upgrade target can be stated from them. Check the vendor's advisory for the current fix status before deciding on an action.Source: github.com, code.ffmpeg.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data