XSS in B3log Siyuan
CVE-2026-34605
SiYuan is a personal knowledge management system. From version 3.6.0 to before version 3.6.2, the SanitizeSVG function introduced in version 3.6.0 to fix XSS in the unauthenticated /api/icon/getDynamicIcon endpoint can be bypassed by using namespace-prefixed element names such as <x:script xmlns:x="http://www.w3.org/2000/svg">. The Go HTML5 parser records the element's tag as "x:script" rather than "script", so the tag check passes it through. The SVG is served with Content-Type: image/svg+xml and no Content Security Policy; when a browser opens the response directly, its XML parser resolves the prefix to the SVG namespace and executes the embedded script. This issue has been patched in version 3.6.2.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.006 (46.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
- B3log Siyuan
- Siyuan-Note Siyuan — versions >= 3.6.0, < 3.6.2
Weakness classification (CWE)
References
- github.com/siyuan-note/siyuan/security/advisories/GHSA-73g7-86qr-jrg3 (Exploit, Vendor Advisory)
- github.com/siyuan-note/siyuan/issues/17246 (Issue Tracking)
- github.com/siyuan-note/siyuan/releases/tag/v3.6.2 (Release Notes)
Frequently asked questions
- What is CVE-2026-34605?
- CVE-2026-34605 is a medium-severity vulnerability in B3log Siyuan, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-03-31.
- How severe is CVE-2026-34605?
- Medium severity. CVSS v3 base score is 6.1 out of 10.