FFmpeg through 9.0.2 contains an uninitialized stack memory disclosure vulnerability in old_codec23() of libavcodec/sanm.c that leaks stack bytes into decoded frames
Source GCVE Database
Not known to be exploited · CVSS 4.8 Medium · patch available : update FFmpeg when convenient.
Data as of 9 Nov 2026, 22:20 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 4.8 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 3.3 |
- Patch
- Available
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 9 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 9 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| FFmpegFFmpeg | Affected
| Fixed in– |
GitHubFFmpegpkg:github/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.
Description
FFmpeg through 9.0.2 contains an uninitialized stack memory disclosure vulnerability in old_codec23() of libavcodec/sanm.c that leaks stack bytes into decoded frames. Attackers can supply a crafted LucasArts SMUSH/SANM animation using codec 23 with an inline table to expose decoder process stack memory in output video.
References
- nvd.nist.gov/vuln/detail/CVE-2026-125266 (opens in a new tab)
- github.com/FFmpeg/FFmpeg/commit/d42cb1925987cc27899441ce39fa7bd2647dc72e (opens in a new tab)
- code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25718 (opens in a new tab)
- github.com/FFmpeg/FFmpeg (opens in a new tab)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/sanm.c (opens in a new tab)
- vulncheck.com/advisories/ffmpeg-through-9.0.2-uninitialized-stack-memory-disclosure-via-sanm-codec-23 (opens in a new tab)