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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.9 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS

• CVE-2026-54067: 0.38% estimated exploitation activity in the next 30 days; percentile 32.21 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A CSS snippet body containing </style breaks out of its surrounding <style tag when renderSnippet() interpolates it via insertAdjacentHTML. A payload like </style<img src=x onerror="..." runs arbitrary JavaScript in the renderer. On Electron desktop builds the renderer runs with nodeIntegration:true, so require('childprocess') 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…

Published by the source

10 Jul 2026, 19:25 UTC

Last modified by the source

10 Jul 2026, 19:25 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-mvjr-vv3c-w4qv

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# Patch Next advisory brief: CVE-2026-54067

Advisory: SiYuan: Stored XSS to RCE via CSS-snippet breakout in renderSnippet()
IDs: CVE-2026-54067, GHSA-mvjr-vv3c-w4qv
Record: https://patchnext.com/advisories/cve-2026-54067 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/siyuan-note/siyuan/kernel 0.0.0-20260628153353-2d5d72223df4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/siyuan-note/siyuan/kernel: affected < 0.0.0-20260628153353-2d5d72223df4; fixed in 0.0.0-20260628153353-2d5d72223df4

## Suggested inspection (read-only)
- Go github.com/siyuan-note/siyuan/kernel: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/siyuan-note/siyuan/kernel.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mvjr-vv3c-w4qv (GitHub-reviewed advisory GHSA-mvjr-vv3c-w4qv lists affected ranges: Go github.com/siyuan-note/siyuan/kernel >=0 <0.0.0-20260628153353-2d5d72223df4)

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