Use After Free Vulnerability in FFmpeg's MJPEG Decoding Functionality
CVE-2026-125255

5.8MEDIUM

Key Information:

Vendor

Ffmpeg

Status
Ffmpeg
Vendor
CVE Published:
9 November 2026

What is CVE-2026-125255?

FFmpeg versions up to 9.0.2 have a use after free vulnerability found in the MJPEG decoding process within libavcodec/mjpegdec.c. This vulnerability occurs when an attacker sends a Start of Frame (SOF) marker without a corresponding Start of Image (SOI) marker. As a result, the function ff_mjpeg_decode_sof() attempts to reference a freed raw_image_buffer pointer, which can lead to crashes in applications or potential leakage of sensitive heap memory contents when processing maliciously crafted MJPEG streams.

Affected Version(s)

FFmpeg 0 <= 9.0.2

References

https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25231
issue-tracking
https://github.com/FFmpeg/FFmpeg/commit/f58a6776546567367...
patch
https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/m...
technical-description

CVSS V4

Score:
5.8
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
High
Attack Vector:
Local
Attack Complexity:
High
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Joshua Rogers (AISLE Research)
Michael Niedermayer
.