CVE-2026-125742
7-Zip before 26.06 Heap Out-of-Bounds Write via LZX Decoder in CAB Extraction
7-Zip before 26.06 contains a heap out-of-bounds write vulnerability in the LZX decoder that lets attackers corrupt memory when a continuation CAB volume declares a smaller window. Attackers can entice victims to extract crafted multi-volume CAB archives, where a stale _pos value bypasses bounds checks, enabling arbitrary code execution.
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 |
|---|---|---|
| 7-Zip 7-Zip |
≥ 0; < 26.06 (affected, custom)
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 / 8.5 high |
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N | CNA: VulnCheck |
| 3.1 / 7.8 high |
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H | CNA: VulnCheck |
| 4.0 / 8.5 high |
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/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 / 7.8 high |
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H | NVD: [email protected] |
Exploit evidence
- https://potion-brew.pages.dev/posts/7zip-cab-lzx-window-desync-rce/
exploit · CNA: VulnCheck
References
- https://github.com/ip7z/7zip/commit/d3296e39e1f1f92c7b41c0c3848e65640428d42dCNA: VulnCheck · patch
- https://github.com/ip7z/7zip/releases/tag/26.06CNA: VulnCheck · release-notes
- https://github.com/ip7z/7zip/blob/26.05/CPP/7zip/Compress/LzxDecoder.cpp#L1496-L1513CNA: VulnCheck · product
- https://potion-brew.pages.dev/posts/7zip-cab-lzx-window-desync-rce/CNA: VulnCheck · technical-description, exploit
- https://www.vulncheck.com/advisories/7-zip-before-26.06-heap-out-of-bounds-write-via-lzx-decoder-in-cab-extractionCNA: VulnCheck · third-party-advisory
- https://github.com/ip7z/7zip/blob/26.05/CPP/7zip/Compress/LzxDecoder.cpp#L1496-L1513[email protected]
- https://github.com/ip7z/7zip/commit/d3296e39e1f1f92c7b41c0c3848e65640428d42d[email protected]
- https://github.com/ip7z/7zip/releases/tag/26.06[email protected]
- https://potion-brew.pages.dev/posts/7zip-cab-lzx-window-desync-rce/[email protected]
- https://www.vulncheck.com/advisories/7-zip-before-26.06-heap-out-of-bounds-write-via-lzx-decoder-in-cab-extraction[email protected]
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