UBUNTU-CVE-2026-66038

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UBUNTU-CVE-2026-66038

Summary:

Details: 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.

References: https://ubuntu.com/security/CVE-2026-66038, https://www.cve.org/CVERecord?id=CVE-2026-66038, https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23626, https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/e7cbfd1c507b57a806a5825b87d609963e862c8c, https://www.vulncheck.com/advisories/ffmpeg-lcl-zlib-video-decoder-information-disclosure-via-lcldec-c, https://ubuntu.com/security/notices/USN-8671-1, https://ubuntu.com/security/notices/USN-8738-1