SiYuan up to 3.5.9 Endpoint /api/icon/getDynamicIcon cross site scripting

Summaryinfo

A vulnerability identified as problematic has been detected in SiYuan up to 3.5.9. This impacts an unknown function of the file /api/icon/getDynamicIcon of the component Endpoint. Performing a manipulation results in cross site scripting. This vulnerability is known as CVE-2026-31807. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in SiYuan up to 3.5.9. It has been classified as problematic. This affects some unknown functionality of the file /api/icon/getDynamicIcon of the component Endpoint. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) blocks dangerous elements (<script>, <iframe>, <foreignobject>) and removes on* event handlers and javascript: in href attributes. However, it does NOT block SVG animation elements (<animate>, <set>) which can dynamically set attributes to dangerous values at runtime, bypassing the static sanitization. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint (type=8), creating a reflected XSS. This is a bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in v3.5.10.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-31807 since 03/09/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 3.5.10 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-10892). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Name

• SiYuan

Version

• 3.5.0
• 3.5.1
• 3.5.2
• 3.5.3
• 3.5.4
• 3.5.5
• 3.5.6
• 3.5.7
• 3.5.8
• 3.5.9

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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