siyuan-note SiYuan up to 3.8.3 Gutter Button button.ts innerHTML data-subtype cross site scripting

Summaryinfo

A vulnerability was found in siyuan-note SiYuan up to 3.8.3. It has been classified as problematic. The impacted element is the function innerHTML of the file app/src/protyle/gutter/button.ts of the component Gutter Button. The manipulation of the argument data-subtype leads to cross site scripting. This vulnerability is documented as CVE-2026-100639. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in siyuan-note SiYuan up to 3.8.3. This issue affects the function innerHTML of the file app/src/protyle/gutter/button.ts of the component Gutter Button. The manipulation of the argument data-subtype with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to 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. Impacted is integrity. The summary by CVE is:

SiYuan v3.8.3 fails to HTML-escape the data-subtype attribute when generating gutter-button markup (app/src/protyle/gutter/button.ts, assigned via innerHTML in app/src/protyle/gutter/index.ts) from content pasted as plain-text Markdown containing a Kramdown inline attribute list (IAL). Because the shared Lute renderer parses Kramdown IAL from text/plain input, an attacker-supplied Markdown snippet using entity-encoded quotes in data-subtype breaks out of the attribute value when the gutter markup is re-parsed by the browser, injecting additional attributes such as autofocus and onfocus. If a victim pastes the crafted Markdown and the affected gutter control receives focus, the injected handler executes; in the Electron desktop application, where the main BrowserWindow enables Node integration and disables context isolation, this results in JavaScript execution with renderer Node.js privileges (remote code execution). Fixed in v3.8.4.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-100639 since 09/26/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful 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 3.8.4 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• siyuan-note

Name

• SiYuan

Version

• 3.8.0
• 3.8.1
• 3.8.2
• 3.8.3

Website

• Product: https://github.com/siyuan-note/siyuan/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion