CVE-2026-125197
FFmpeg through 9.0.2 Heap Out-of-Bounds Read via LCL/ZLIB Multithread Decoding
CVSS Score
6.1
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-191 |
| Vendor | ffmpeg |
| Product | ffmpeg |
| Published | Nov 9, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Affected Versions
FFmpeg / FFmpeg
0 ≤ 9.0.2
References
code.ffmpeg.org: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25020 github.com: https://github.com/FFmpeg/FFmpeg/commit/12e5d4ec98b7add7bcac9d8131d9a6dfb2549966 github.com: https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/lcldec.c#L287 github.com: https://github.com/FFmpeg/FFmpeg vulncheck.com: https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-out-of-bounds-read-via-lcl-zlib-multithread-decoding
Credits
Claude and Ada Logics 🔍 Joshua Rogers (AISLE Research) Michael Niedermayer