CVE-2026-66394

critical · 9.3

SiYuan before v3.7.3 contains stored and reflected cross-site scripting vulnerabilities in SVG sanitization that allows authenticated attackers to execute scripts by bypassing the HTML parser-based cleaner. Attackers can hide script tags within desc, style, or noscript elements which the HTML parser treats as raw text but browsers interpret as executable SVG content when served as image/svg+xml, enabling script execution in the application origin.

9.3

CVSS

0.3%

EPSS (exploit prob.)

19th

EPSS percentile

2026-07-27

Published

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Weaknesses

CWE-79

References

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f
https://www.vulncheck.com/advisories/siyuan-before-stored-and-reflected-xss-via-svg-sanitizer-bypass
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-66394