XSS in B3log Siyuan
CVE-2026-33066
SiYuan is a personal knowledge management system. In versions 3.6.0 and below, the backend renderREADME function uses lute.New() without calling SetSanitize(true), allowing raw HTML embedded in Markdown to pass through unmodified. The frontend then assigns the rendered HTML to innerHTML without any additional sanitization. A malicious package author can embed arbitrary JavaScript in their README that executes when a user clicks to view the package details. Because SiYuan's Electron configuration enables nodeIntegration: true with contextIsolation: false, this XSS escalates directly to full Remote Code Execution. The issue was patched in version 3.6.1.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.006 (44.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H.
Affected products
- B3log Siyuan
- Siyuan-note Siyuan — versions < 3.6.1
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-33066?
- CVE-2026-33066 is a critical-severity vulnerability in B3log Siyuan, classified under Cross-site Scripting. CVSS score: 9.0/10. Published 2026-03-20.
- How severe is CVE-2026-33066?
- Critical severity. CVSS v3 base score is 9.0 out of 10.