vulnerability / NVI-00017559 / Revision 1
SiYuan: Stored XSS to RCE via CSS-snippet breakout in renderSnippet()
GitHub lists this reviewed advisory for github.com/siyuan-note/siyuan/kernel. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
9.9 critical
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
github.com/siyuan-note/siyuan/kernel
source listed< 0.0.0-20260628153353-2d5d72223df4
### Summary A CSS snippet body containing `` breaks out of its surrounding `` 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. ### Details Affected: - HEAD `96dfe0b` (v3.6.5, 2026-04-21) - Sink: `app/src/config/util/snippets.ts:32` - Source: `/api/snippet/getSnippet`, backed by `data/snippets/conf.json` - Default config: `EnabledCSS: true`, `EnabledJS: true` at `kernel/conf/snippet.go:26-27` - Electron config: `nodeIntegration:true`, `contextIsolation:false`, `webSecurity:false` on every `BrowserWindow` in `app/electron/ma
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-mvjr-vv3c-w4qv ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
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