CVE-2026-66038
FFmpeg LCL/ZLIB Video Decoder Information Disclosure via lcldec.c
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.
| CWE | CWE-908 |
| Vendor | ffmpeg |
| Product | ffmpeg |
| Published | Jul 24, 2026 |
| Last Updated | Jul 24, 2026 |
Get instant alerts for ffmpeg ffmpeg
Be the first to know when new medium vulnerabilities affecting ffmpeg ffmpeg are published — delivered to Slack, Telegram or Discord.
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N