CVE-2026-66394CWE-79cross-site-scripting

CVE-2026-66394

High · published July 27, 2026

CVSS v3.1
8.7
EPSS
0%
Percentile
25.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.7 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00337 · 25.8th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-07-27T20:18Z
References (3)
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f · [email protected]https://www.vulncheck.com/advisories/siyuan-before-stored-and-reflected-xss-via-svg-sanitizer-bypass · [email protected]https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f · 134c704f-9b21-4f2e-91b3-4a467353bcc0
EPSS history
Timeline
  • 27 JUL 15:43Z
    SiYuan before v3.7.3 Stored and Reflected XSS via SVG Sanitizer Bypass
    cvelistv5