Libav: FFmpeg 4.4 through 9.0.2 contains a use of uninitialized variable vulnerability in the CDXL decoder that leaks
Affects libavSource GCVE Database
Not known to be exploited · CVSS 6.8 Medium.
Data as of 5 Nov 2026, 12:48 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 6.8 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 5.5 |
| CNA | CVSS 4.0 | 6.8 |
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 1 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10ffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu Pro 26.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/resoluteOther threats | Affected
| Fixed in– |
Ubuntu Pro 24.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSffmpegpkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps/bionicOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Until a fix is available, avoid processing untrusted CDXL files with affected FFmpeg versions.
Description
FFmpeg versions 4.4 through 9.0.2 contain a use of uninitialized variable vulnerability in the CDXL decoder. This flaw causes stack memory to leak into decoded pixels via unfilled HAM palette entries. An attacker can craft a specially designed type-0 CDXL file to expose stack bytes and pointer fragments in the BGR24 output.
References
- ubuntu.com/security/CVE-2026-120246 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-120246 (opens in a new tab)
- code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24856 (opens in a new tab)
- github.com/FFmpeg/FFmpeg (opens in a new tab)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cdxl.c (opens in a new tab)
- github.com/FFmpeg/FFmpeg/commit/47313ad3f9f33b892384b976fb7c09b3c85fd74e (opens in a new tab)
- vulncheck.com/advisories/ffmpeg-4.4-through-9.0.2-uninitialized-memory-disclosure-via-cdxl-ham-decoder (opens in a new tab)