CVE-2026-125742 PUBLISHED

7-Zip before 26.06 Heap Out-of-Bounds Write via LZX Decoder in CAB Extraction

Assigner: VulnCheck
Reserved: 10.11.2026 Published: 10.11.2026 Updated: 10.11.2026

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.

CVSS Vector: 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
CVSS Score: 8.5

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Local	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	None
User Interaction	Passive

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS Score: 7.8

Attack Vector	Local	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	High
Privileges Required	None	Integrity Impact	High
User Interaction	Required	Availability Impact	High

CVSS 3.1

Product Status

Vendor	7-Zip
Product	7-Zip
Versions	Default: unaffected affected from 0 to 26.06 (excl.)

Credits

Nguyễn Trần Thanh Lâm of Nanyang Technological University, and other researchers who wished to remain anonymous finder

References

Problem Types

Out-of-bounds Write CWE