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CWE

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CVE-2026-42171

Published: Apr 24, 2026

Modified: Apr 25, 2026

PUBLISHED

CVSS v3.1

7.8

HIGH

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).

Vendor	Product	Versions
Nullsoft	Nullsoft Scriptable Install System	affected `3.06.1 - < 3.12`

Weaknesses (CWE)

CVSS v3.1 Details

CVSS v3.1 Vector

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

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

References

https://nsis.sourceforge.io/Docs/AppendixF.html#v3.12-cl

https://github.com/NSIS-Dev/nsis/commit/8e6f02205d5f22da6c7855dbfe59b2af667330ca

https://github.com/NSIS-Dev/nsis/blob/7359413009afd4f0fff472d841fc2f2cc0e0a5f8/Source/exehead/util.c#L475-L484

https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-gettempfilename

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