FFmpeg 4.4 through 9.0.2 contains a use of uninitialized variable vulnerability in the CDXL decoder that leaks stack
Affects FFmpegSource GCVE Database
Not known to be exploited · CVSS 6.8 Medium.
Data as of 1 Nov 2026, 04:22 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 6.8 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 5.5 |
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 31 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
GitHubffmpeg/FFmpegpkg:github/ffmpeg/FFmpegOther 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 or use alternative decoders if possible.
Description
FFmpeg versions 4.4 through 9.0.2 have a vulnerability in the CDXL decoder where uninitialized variables lead to leakage of stack memory into decoded pixel data. This occurs via unfilled HAM palette entries, allowing crafted CDXL files to expose stack bytes and pointer fragments in the output.
References
- nvd.nist.gov/vuln/detail/CVE-2026-120246 (opens in a new tab)
- github.com/FFmpeg/FFmpeg/commit/47313ad3f9f33b892384b976fb7c09b3c85fd74e (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)
- vulncheck.com/advisories/ffmpeg-4.4-through-9.0.2-uninitialized-memory-disclosure-via-cdxl-ham-decoder (opens in a new tab)