CVE-2026-33976

Notesnook is a note-taking app. Prior to version 3.3.11 on Web/Desktop and 3.3.17 on Android/iOS, a stored XSS in the Web Clipper rendering flow can be escalated to remote code execution in the desktop app. The root cause is that the clipper preserves attacker-controlled attributes from the source page’s root element and stores them inside web-clip HTML. When the clip is later opened, Notesnook renders that HTML into a same-origin, unsandboxed iframe using `contentDocument.write(...)`. Event-handler attributes such as `onload`, `onclick`, or `onmouseover` execute in the Notesnook origin. In the desktop app, this becomes RCE because Electron is configured with `nodeIntegration: true` and `contextIsolation: false`. Version 3.3.11 Web/Desktop and 3.3.17 on Android/iOS patch the issue.

Score

CVSS 3.1 9.7 Critical

Status

Analyzed - security-advisories@github.com

Published

2026-03-27

Last modified

2026-10-26

Weaknesses

CWE-79, CWE-94

Affected products

• Notesnook Desktop (Streetwriters)
• Notesnook Iosandroid (Streetwriters)
• Notesnook Mobile (Streetwriters)
• Notesnook Webdesktop (Streetwriters)

References

• https://github.com/streetwriters/notesnook/security/advisories/GHSA-f42f-phvp-43x5