CVE-2026-42171
high
CVSS v3
7.8
CVSS v4 NEW
—
VIR risk
7.8
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).
Predictions
Exploit likelihood
75%
Patch ETA
—
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | bookworm | affected | |
| debian | bullseye | affected | |
| debian | forky | fixed | 3.12-1 |
| debian | sid | fixed | 3.12-1 |
| debian | trixie | affected | |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| nullsoft | nullsoft_scriptable_install_system | {"startIncluding":"3.06.1","endExcluding":"3.12"} | 3.12 |
References
- https://github.com/NSIS-Dev/nsis/blob/7359413009afd4f0fff472d841fc2f2cc0e0a5f8/Source/exehead/util.c#L475-L484
- https://github.com/NSIS-Dev/nsis/commit/8e6f02205d5f22da6c7855dbfe59b2af667330ca
- https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-gettempfilename
- https://nsis.sourceforge.io/Docs/AppendixF.html#v3.12-cl
- https://security-tracker.debian.org/tracker/CVE-2026-42171
CWEs
CWE-427
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.