CVE-2026-54067
Published: 24 June 2026
Summary
CVE-2026-54067 is a critical-severity Cross-site Scripting (CWE-79) vulnerability. Its CVSS base score is 9.9 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 22.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-39123
Vulnerability details
SiYuan is an open-source personal knowledge management system. Prior to 3.7.0, CSS snippet body containing </style> breaks out of its surrounding <style> tag when renderSnippet() interpolates it via insertAdjacentHTML. A payload like runs arbitrary JavaScript in the renderer. On Electron…
more
desktop builds the renderer runs with nodeIntegration:true, so require('child_process') is reachable from the injected handler and the XSS chains to host RCE. Snippets sync via the workspace repository, so an attacker with write access to any synced workspace plants the payload once and it fires on every device that pulls. The bug also bypasses the user's enabledCSS / enabledJS separation. A user who turned enabledJS off was making a deliberate call not to run untrusted JavaScript; the CSS path runs it anyway. This vulnerability is fixed in 3.7.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
XSS via snippet content injection (T1659) directly enables RCE in the Electron renderer; the flaw is in a syncable public-facing app component (T1190).
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.
Requires documented secure initialization practices and avoidance of insecure defaults in configuration baselines.
Reviewing and updating baseline when components are installed or upgraded prevents initialization with insecure defaults.
Requiring explicit configuration to minimal functionality overrides insecure defaults that would otherwise enable excess capabilities.
Tailoring replaces or augments insecure default initializations with system-specific values and compensating controls before deployment.
Central configuration overrides or replaces insecure default initializations that would otherwise be left unchanged on each system.
SCRM practices during acquisition and configuration management address insecure default initializations shipped by vendors.
Scans detect resources initialized with insecure defaults that create exploitable conditions.