Vulnerability Description
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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Ffmpeg | Ffmpeg | <= 8.1.2 |
Related Weaknesses (CWE)
References
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/e7cbfd1c507b57a806a5825b87d609963e8Patch
- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23626Issue TrackingPatch
- https://www.vulncheck.com/advisories/ffmpeg-lcl-zlib-video-decoder-information-dThird Party Advisory
FAQ
What is CVE-2026-66038?
CVE-2026-66038 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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 v...
How severe is CVE-2026-66038?
CVE-2026-66038 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-66038?
Check the references section above for vendor advisories and patch information. Affected products include: Ffmpeg Ffmpeg.