CVE-2026-42171
NSIS Privilege Escalation Vulnerability
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).
INFO
Published Date :
April 24, 2026, 10:16 p.m.
Last Modified :
April 24, 2026, 10:16 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-42171
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 8254265b-2729-46b6-b9e3-3dfca2d5bfca | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update NSIS to version 3.12 or later.
- Verify temporary directory access controls.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-42171.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-42171 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-42171
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-42171 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-42171 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Apr. 24, 2026
Action Type Old Value New Value Added 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). Added CVSS V3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Added CWE CWE-427 Added Reference https://github.com/NSIS-Dev/nsis/blob/7359413009afd4f0fff472d841fc2f2cc0e0a5f8/Source/exehead/util.c#L475-L484 Added Reference https://github.com/NSIS-Dev/nsis/commit/8e6f02205d5f22da6c7855dbfe59b2af667330ca Added Reference https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-gettempfilename Added Reference https://nsis.sourceforge.io/Docs/AppendixF.html#v3.12-cl