CVE-2026-125197

medium

Description

FFmpeg through 9.0.2 contains an integer underflow in decode_frame() in libavcodec/lcldec.c that allows attackers to trigger a heap out-of-bounds read via short ZLIB packets with FLAG_MULTITHREAD. Attackers can supply a crafted AVI or MKV file with an LCL video stream whose packet is shorter than 8 bytes, bypassing length clamping to crash the decoding application.

References

https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-out-of-bounds-read-via-lcl-zlib-multithread-decoding

https://github.com/FFmpeg/FFmpeg/commit/12e5d4ec98b7add7bcac9d8131d9a6dfb2549966

https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/lcldec.c#L287

https://github.com/FFmpeg/FFmpeg

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-120286

https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25020

Details

Source: Mitre, NVD

Published: 2026-11-09

Updated: 2026-11-10

Risk Information

CVSS v2

Base Score: 5.6

Vector: CVSS2#AV:L/AC:L/Au:N/C:P/I:N/A:C

Severity: Medium

CVSS v3

Base Score: 6.1

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H

Severity: Medium

CVSS v4

Base Score: 6.9

Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N

Severity: Medium

EPSS

EPSS: 0.00135