Uninitialized Stack Memory Disclosure Vulnerability in FFmpeg by FFmpeg
CVE-2026-125266

4.8MEDIUM

Key Information:

Vendor

Ffmpeg

Status
Ffmpeg
Vendor
CVE Published:
9 November 2026

What is CVE-2026-125266?

FFmpeg versions prior to 9.0.2 are susceptible to a vulnerability in the old_codec23() function within libavcodec/sanm.c. This issue allows attackers to exploit crafted LucasArts SMUSH/SANM animation files that utilize codec 23, potentially leaking sensitive stack memory into the decoded video output. By manipulating this process with an inline table, an adversary could gain visibility into stack bytes that should otherwise remain confidential, posing risks to user data security.

Affected Version(s)

FFmpeg 8.0 <= 9.0.2

References

https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25718
issue-tracking
https://github.com/FFmpeg/FFmpeg/commit/d42cb1925987cc278...
patch
https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/s...
technical-description

CVSS V4

Score:
4.8
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
None
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Joshua Rogers (AISLE Research)
Michael Niedermayer
.