CVE-2026-66395
Reflected XSS in SiYuan via siyuan:// deep link enabling Node.js code execution
Is CVE-2026-66395 being exploited?
Not confirmed. CVE-2026-66395 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.33% probability of exploitation in the next 30 days.
How severe is CVE-2026-66395?
CVE-2026-66395 is rated Critical with a CVSS score of 9.4. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-66395?
Yes. A fix has been recorded for CVE-2026-66395. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-66395 affect?
CVE-2026-66395 affects SiYuan Desktop < v3.7.2, bazaar plugin, Electron-based SiYuan installations. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-66395?
Update SiYuan to v3.7.2+; block untrusted siyuan:// links and disable Node integration.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Crafted siyuan:// deep link injects HTML that executes with Node.js access, enabling remote code execution and full system compromise.
Immediate action required
- affected< 3.7.2
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.