FFmpeg through 9.0.2 Uninitialized Memory Disclosure via JPEG-LS Decoder

Advisories

FFmpeg through 9.0.2 Uninitialized Memory Disclosure via JPEG-LS Decoder

Severity: medium
Date: 11/9/2026
Affecting: FFmpeg <= 9.0.2
CVE: CVE-2026-125243
CWE: CWE-908 Use of Uninitialized Resource
CVSS: 4.8
CVSS V4 Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
References: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25303
Patch Commit
https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/jpeglsdec.c#L483
https://github.com/FFmpeg/FFmpeg
Credit: Joshua Rogers (AISLE Research), Martin Mirchev
Description: FFmpeg through 9.0.2 contains an uninitialized memory disclosure vulnerability in ff_jpegls_decode_picture() in libavcodec/jpeglsdec.c, which decodes 16-bit line-interleaved JPEG-LS scans as 8-bit samples. Attackers can supply a crafted single-component JPEG-LS image with the ILV byte set to 1, causing decoded GRAY16 frames to expose leftover heap memory.

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