SiYuan: Stored XSS to RCE via CSS-snippet <style> breakout in renderSnippet()

Summary

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 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.

Timeline

1. Jun 24, 2026, 9:14 PM UTCCVE published
2. Jun 25, 2026, 3:29 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: no · Technical impact: total

3. Jun 25, 2026, 3:29 PM UTCRecord last updated

Affected versions

• siyuan-note siyuan

  fixed in 3.7.0

• github.com/siyuan-note/siyuan/kernelGo

  fixed in 0.0.0-20260628153353-2d5d72223df4

References 1