CVE-2026-31809
Severity CVSS v4.0:
MEDIUM
Type:
CWE-79
Cross-Site Scripting (XSS)
Publication date:
10/03/2026
Last modified:
11/03/2026
Description
SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) checks href attributes for the javascript: prefix using strings.HasPrefix(). However, inserting ASCII tab (	), newline (
), or carriage return (
) characters inside the javascript: string bypasses this prefix check. Browsers strip these characters per the WHATWG URL specification before parsing the URL scheme, so the JavaScript still executes. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint, creating a reflected XSS. This is a second bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in 3.5.10.
Impact
Base Score 4.0
6.40
Severity 4.0
MEDIUM
Base Score 3.x
6.10
Severity 3.x
MEDIUM
Vulnerable products and versions
| CPE | From | Up to |
|---|---|---|
| cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:* | 3.5.10 (excluding) |
To consult the complete list of CPE names with products and versions, see this page