CVE-2026-125101
FFmpeg through 9.0.2 VMnc Decoder Uninitialized Heap Memory Disclosure
FFmpeg through 9.0.2 contains an information disclosure vulnerability in the VMnc decoder in libavcodec/vmnc.c that restores an unwritten cursor save area into later frames. Attackers can supply a crafted VMnc stream where a frame fails after loading a cursor shape, causing uninitialized heap bytes from screendta to appear in decoded output.
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: VulnCheckAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| FFmpeg FFmpeg ffmpeg/ffmpeg
github |
≥ 0; ≤ 9.0.2 (affected, semver)
Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 4.8 medium |
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N | CNA: VulnCheck |
| 3.1 / 3.3 low |
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N | CNA: VulnCheck |
| 4.0 / 4.8 medium |
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/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 | NVD: [email protected] |
| 3.1 / 3.3 low |
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25716CNA: VulnCheck · issue-tracking
- https://github.com/FFmpeg/FFmpeg/commit/50865f20b1f474e6b11735c88f668751bc9aa528CNA: VulnCheck · patch
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/vmnc.c#L348CNA: VulnCheck · technical-description
- https://github.com/FFmpeg/FFmpegCNA: VulnCheck · product
- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-vmnc-decoder-uninitialized-heap-memory-disclosureCNA: VulnCheck · third-party-advisory
- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25716[email protected]
- https://github.com/FFmpeg/FFmpeg[email protected]
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/vmnc.c#L348[email protected]
- https://github.com/FFmpeg/FFmpeg/commit/50865f20b1f474e6b11735c88f668751bc9aa528[email protected]
- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-vmnc-decoder-uninitialized-heap-memory-disclosure[email protected]
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