CVE-2026-82649: SiYuan before 3.8.1 Local Privilege Escalation via Uncontrolled Search Path

Severity: high (CVSS 7.0 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-30 · updated 2026-09-01
Weakness: CWE-427

Description

SiYuan Windows installer before version 3.8.1 (affected versions >= 2.0.14) contains an uncontrolled search path element vulnerability in its NSIS installer, which invokes system executables such as TASKKILL by name rather than by absolute path. Because NSIS nsExec::Exec resolves these calls using a search path that includes the installer's own launch directory ahead of System32, an attacker who plants a malicious executable (e.g., a renamed TASKKILL.exe) in that directory can have it executed when the installer runs. These calls occur in electron-builder's preInit hook before the license page is displayed, and with an all-users (elevated) install the planted binary executes with an elevated token, resulting in local privilege escalation.

Affected products

siyuan-note siyuan: from 2.0.14 before 3.8.1 — fixed in 3.8.1

How to fix

Upgrade to a fixed version: siyuan-note siyuan 3.8.1. Check the vendor advisory for mitigations.

References

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