CVE-2026-66038: high-severity vulnerability in FFmpeg
FFmpeg LCL/ZLIB Video Decoder Information Disclosure via lcldec.c
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.1epss 0.2%
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Affected products
FFmpeg · FFmpegRelated CVEs — FFmpeg
In the same product, most dangerous first.
CVE-2026-8461HIGHHeap out-of-bounds write via odd slice_height in FFmpeg MagicYUV decoderEPSS 1.6%CVE-2026-64831HIGHFFmpeg 8.0 - 8.1.2 Stack Buffer Overflow in Vulkan HEVC DecoderEPSS 0.9%CVE-2026-66040HIGHFFmpeg Heap Out-of-Bounds Write via PNG/APNG eXIf EncoderEPSS 0.8%CVE-2026-64834HIGHFFmpeg 0.6.3 - 8.1.2 Infinite Loop DoS via RTP/ASF DemuxerEPSS 0.7%CVE-2026-75143CRITICALFFmpeg Heap Buffer Overflow via RIST Protocol ReaderEPSS 0.7%CVE-2026-64830HIGHFFmpeg 2.1 - 8.1.2 Heap Buffer Overflow via VobSub Subtitle DemuxerEPSS 0.6%