CVE-2026-42171: CWE-427 Uncontrolled Search Path Element in Nullsoft Nullsoft Scriptable Install System
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).
AI Analysis
Technical Summary
The vulnerability CVE-2026-42171 in NSIS 3.06.1 involves an uncontrolled search path element due to the use of the Low IL temporary directory when executing with SYSTEM privileges. This behavior can be triggered if the internal function my_GetTempFileName returns 0, allowing local attackers to influence the search path and potentially escalate privileges. The vulnerability is categorized under CWE-427 and has a CVSS 3.1 base score of 7.8, indicating high severity. No official patch or remediation level has been documented, and the product is not a cloud service, so remediation depends on vendor updates or user mitigation.
Potential Impact
Successful exploitation of this vulnerability could allow a local attacker to gain elevated privileges on the affected system by manipulating the temporary directory used by NSIS when running as SYSTEM. This could lead to full system compromise, including confidentiality, integrity, and availability impacts as reflected by the CVSS score. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no official fix or remediation level is provided, users should monitor Nullsoft's advisories for updates. Until a patch is available, restricting local user access and limiting execution of NSIS installers with SYSTEM privileges may reduce risk.
CVE-2026-42171: CWE-427 Uncontrolled Search Path Element in Nullsoft Nullsoft Scriptable Install System
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).
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-42171 in NSIS 3.06.1 involves an uncontrolled search path element due to the use of the Low IL temporary directory when executing with SYSTEM privileges. This behavior can be triggered if the internal function my_GetTempFileName returns 0, allowing local attackers to influence the search path and potentially escalate privileges. The vulnerability is categorized under CWE-427 and has a CVSS 3.1 base score of 7.8, indicating high severity. No official patch or remediation level has been documented, and the product is not a cloud service, so remediation depends on vendor updates or user mitigation.
Potential Impact
Successful exploitation of this vulnerability could allow a local attacker to gain elevated privileges on the affected system by manipulating the temporary directory used by NSIS when running as SYSTEM. This could lead to full system compromise, including confidentiality, integrity, and availability impacts as reflected by the CVSS score. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no official fix or remediation level is provided, users should monitor Nullsoft's advisories for updates. Until a patch is available, restricting local user access and limiting execution of NSIS installers with SYSTEM privileges may reduce risk.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mitre
- Date Reserved
- 2026-04-24T21:20:35.145Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69ebe24487115cfb68759c48
Added to database: 4/24/2026, 9:36:04 PM
Last enriched: 4/24/2026, 9:51:03 PM
Last updated: 4/24/2026, 11:49:05 PM
Views: 7
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