Is CVE-2026-42171 in the CISA KEV catalog?

No. CVE-2026-42171 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-42171?

CVE-2026-42171 has a CVSS v3 base score of 7.8 (HIGH).

What is the EPSS score for CVE-2026-42171?

CVE-2026-42171 has an EPSS score of 0.21% (11th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42171?

Upgrade nsis on debian unstable to 3.12-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-42171

HIGH

7.8

CVSS v3

NVD

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).

CWE-427

How to fix

Remediation Available

nsisDebian

Fixed in:3.12-1CVE-2026-42171

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

0.21%probability of exploitation in 30 days

11thpercentile

Low risk: more likely to be exploited than 11% of all known CVEs.

References

Patch1

github.com

Release Notes1

nsis.sourceforge.io

Product2

Embed a live status badge for CVE-2026-42171

Markdown

[![CVE-2026-42171](https://tridentstack.com/cve/badge/CVE-2026-42171.svg)](https://tridentstack.com/cve/CVE-2026-42171)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-42171"><img src="https://tridentstack.com/cve/badge/CVE-2026-42171.svg" alt="CVE-2026-42171"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-18.