CVE-2026-42171 json
NSIS (Nullsoft Scriptable Install System) 3.06.1 before 3.12 sometimes uses the Low IL temp directory when executing as SYSTEM, allowing lo…
published 2026-04-24 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-25637
- cvss
- 7.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 11%
- public exploits
- 0
- none known
Summary
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).
Patch / fix
- Nullsoft Nullsoft Scriptable Install System 3.12
- nsis Debian 14 3.12-1
debian advisories DEBIAN-CVE-2026-42171
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 6 mo ago
Exploit prediction
0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.8 | 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 System
Classification
- Weakness
-
- CWE-427 Uncontrolled Search Path Element
References
-
github.com
/NSIS-Dev/nsis/commit/8e6f02205d5f22da6c7855dbfe59b2af667330ca
patch
-
nsis.sourceforge.io
/Docs/AppendixF.html#v3.12-cl
release-notes
-
github.com
/NSIS-Dev/nsis/blob/7359413009afd4f0fff472d841fc2f2cc0e0a5f8/Source/exehead/util.c#L475-L484
product
-
learn.microsoft.com
/en-us/windows/win32/api/winbase/nf-winbase-gettempfilename
product
Sources
- CVE List CVE-2026-42171
- NVD CVE-2026-42171
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.