CVE-2026-42171
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.8epss 0.2%
exploitation probability
0.2%top 89% of all CVEs
observed exploitation
nono source reports it
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).
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Affected products
Nullsoft · Nullsoft Scriptable Install SystemReferences
https://github.com/NSIS-Dev/nsis/blob/7359413009afd4f0fff472d841fc2f2cc0e0a5f8/Source/exehead/util.c#L475-L484https://github.com/NSIS-Dev/nsis/commit/8e6f02205d5f22da6c7855dbfe59b2af667330cahttps://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-gettempfilenamehttps://nsis.sourceforge.io/Docs/AppendixF.html#v3.12-cl