PT-2026-64414 · FFmpeg · Ffmpeg

Adrian Junge · CVE-2026-66038 · Published 2026-07-24 · Updated 2026-07-24

Mitre

CVSS v3.1

6.5

Medium

Base vector

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

FFmpeg through 8.1.2, fixed in commit 8670835, contains an information disclosure vulnerability in the LCL/ZLIB video decoder that allows attackers to expose uninitialized heap memory by supplying a valid zlib stream that inflates to fewer bytes than the expected frame size. The zlib decomp() function in lcldec.c treats short decompression as non-fatal and continues to the RGB24 conversion path, which copies a full frame's worth of rows from the allocation buffer using original frame dimensions, causing uninitialized heap contents including pointer-derived allocator bytes to be copied into the attacker-observable AVFrame output and potentially defeating ASLR in long-lived media processing services.

Fix

Use of Uninitialized Resource

Weakness Enumeration

CWE-908

Related Identifiers

CVE-2026-66038

Affected Products

Ffmpeg

References · 4

• https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/e7cbfd1c507b57a806a5825b87d609963e862c8c · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-66038 · Security Note
• https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23626 · Note
• https://vulncheck.com/advisories/ffmpeg-lcl-zlib-video-decoder-information-disclosure-via-lcldec-c · Note