SiYuan Has a Stored Cross-Site Scripting (XSS) Vulnerability via Unrestricted SVG File Upload in github.com/siyuan-note/siyuan/kernel

Open Source Vulnerabilities CVE-2026-23645

SiYuan is self-hosted, open source personal knowledge management software. Prior to 3.5.4-dev2, a Stored Cross-Site Scripting (XSS) vulnerability exists in SiYuan Note. The application does not sanitize uploaded SVG files. If a user uploads and views a malicious SVG file (e.g., imported from an untrusted source), arbitrary JavaScript code is executed in the context of their authenticated session. This vulnerability is fixed in 3.5.4-dev2.

Open Source Vulnerabilities GO-2026-4324

SiYuan Has a Stored Cross-Site Scripting (XSS) Vulnerability via Unrestricted SVG File Upload in github.com/siyuan-note/siyuan/kernel

Open Source Vulnerabilities GHSA-pcjq-j3mq-jv5j

### Summary A Stored Cross-Site Scripting (XSS) vulnerability exists in SiYuan Note. The application does not sanitize uploaded SVG files. If a user uploads and views a malicious SVG file (e.g., imported from an untrusted source), arbitrary JavaScript code is executed in the context of their authenticated session. ### Details The application allows authenticated users to upload files, including .svg images, without sanitizing the input to remove embedded JavaScript code (such as <script> tags or event handlers). ### PoC 1. Create a new "Daily note" in the workspace. <img width="1287" height="572" alt="image" src="https://github.com/user-attachments/assets/3a4389b9-695d-4e1b-94dc-72efdb047aa9" /> 2. Create a file named test.svg with malicious JavaScript inside: ``` <svg xmlns="http://www.w3.org/2000/svg" width="200" height="200" viewBox="0 0 124 124" fill="none"> <rect width="124" height="124" rx="24" fill="red"/> <script type="text/javascript"> alert(window.origin); </script> </svg> ``` 3. Upload a file in current daily note: <img width="1617" height="316" alt="image" src="https://github.com/user-attachments/assets/6e14318a-08ec-48e5-b278-9174ad17cfcb" /> <img width="1482" height="739" alt="image" src="https://github.com/user-attachments/assets/95c996e8-5591-436a-9467-ab56c9ffbde0" /> <img width="1321" height="548" alt="image" src="https://github.com/user-attachments/assets/249fb187-3caa-4372-a9c9-56dfda6b8a8f" /> 4. Open the file: - Right-click the uploaded asset in the note. - Select "Export" <img width="934" height="718" alt="image" src="https://github.com/user-attachments/assets/ec943dfa-92ba-47f6-8b1e-56e53f1b0ca6" /> 5. The JavaScript code executes immediately. <img width="1033" height="632" alt="image" src="https://github.com/user-attachments/assets/a1611291-d333-4f8e-9da9-62104aaa1bdd" /> <img width="1381" height="641" alt="image" src="https://github.com/user-attachments/assets/d5018203-dbd0-4285-8702-8cb3e7c5cd07" /> ### Impact The vulnerability allows to upload an SVG file containing malicious scripts. When a user exports this file, the embedded arbitrary JavaScript code is executed within their browser context ### Notes Tested version: <img width="1440" height="534" alt="image" src="https://github.com/user-attachments/assets/a62271e4-6850-4f59-be88-c4f8055429c0" /> ### Solution https://github.com/siyuan-note/siyuan/issues/16844