7-Zip before 26.06 Heap Out-of-Bounds Write via LZX Decoder in CAB Extraction
Summary
| CVE | CVE-2026-125742 |
|---|---|
| State | PUBLISHED |
| Assigner | VulnCheck |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-11-10 12:17:18 UTC |
| Updated | 2026-11-10 12:17:19 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 8.5 HIGH from [email protected]
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
Problem Types: CWE-787 | CWE-787 Out-of-bounds Write
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 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/C... |
| 4.0 | CNA | CVSS | 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 |
| 3.1 | [email protected] | Primary | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
CVSS v4.0 Breakdown
Attack Vector
LocalAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
PassiveConfidentiality
HighIntegrity
HighAvailability
HighSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS: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
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
LowPrivileges Required
NoneUser Interaction
RequiredScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/ip7z/7zip/releases/tag/26.06 | [email protected] | github.com | |
| github.com/ip7z/7zip/commit/d3296e39e1f1f92c7b41c0c3848e65640428d42d | [email protected] | github.com | |
| github.com/ip7z/7zip/blob/26.05/CPP/7zip/Compress/LzxDecoder.cpp | [email protected] | github.com | |
| www.vulncheck.com/advisories/7-zip-before-26.06-heap-out-of-bounds-write-via-lz... | [email protected] | www.vulncheck.com | |
| potion-brew.pages.dev/posts/7zip-cab-lzx-window-desync-rce | [email protected] | potion-brew.pages.dev | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Nguyễn Trần Thanh Lâm of Nanyang Technological University, and other researchers who wished to remain anonymous (en)
There are currently no legacy QID mappings associated with this CVE.