CVE-2026-42171
HIGH
NVD
CVSS Score
7.8
Severity
HIGH
Published
Apr 24, 2026
Vendor
unknown
Description
NSIS (Nullsoft Scriptable Install System) 3.06.1 before 3.12 sometimes uses the Low IL temp directory when executing as SYSTEM, allowing local attackers to gain privileges (if they can cause my_GetTempFileName to return 0, as shown in the references).
References
- https://github.com/NSIS-Dev/nsis/blob/7359413009afd4f0fff472d841fc2f2cc0e0a5f8/Source/exehead/util.c#L475-L484
- https://github.com/NSIS-Dev/nsis/commit/8e6f02205d5f22da6c7855dbfe59b2af667330ca
- https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-gettempfilename
- https://nsis.sourceforge.io/Docs/AppendixF.html#v3.12-cl