Description
FFmpeg versions from 3.0 up to, but not including, 9.0 contain an uninitialized heap memory read vulnerability in the native Screenpresso decoder (libavcodec/screenpresso.c) that allows attackers to recover sensitive memory contents by supplying a crafted SPV1 packet with a valid zlib stream that decompresses fewer bytes than the full frame requires. The screenpresso_decode_frame() function fails to validate the produced byte count before calling av_image_copy_plane() to copy the complete frame dimensions from the persistent ctx->inflated_buf buffer, causing unwritten heap memory from prior allocations or prior frames to be copied into decoded output and potentially exposing sensitive data such as userspace addresses from persistent decoding services.
Affected products
ffmpeg: ffmpeg
References5
- code.ffmpeg.org/FFmpeg/FFmpeg/commit/705890061467ad550ecc1dad5e… Patch
- code.ffmpeg.org/FFmpeg/FFmpeg/commit/9a3202a98b2e095b54dd784c3e… Patch
- code.ffmpeg.org/FFmpeg/FFmpeg/commit/c22667d0fd7916a33fd3e79685… Patch
- code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23896 Issue TrackingPatch
- www.vulncheck.com/advisories/ffmpeg-uninitialized-heap-memory-r… PatchThird Party Advisory
Metrics
- CVSS 3.1
-
5.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - CVSS 4.0
-
6.8
MEDIUM
Score source: CNA
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 7 · as of 12 November 2026
- CWE
- CWE-908
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.