What’s Vulnerable › Vulnerabilities
CVE-2026-33976: Notesnook vulnerable to RCE via stored XSS in Web Clipper rendering
- Severity: critical (CVSS 9.6 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.7% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2026-03-27 · updated 2026-10-26
- Weakness: CWE-79
Description
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.
Affected products
- streetwriters Notesnook Web/Desktop: before 3.3.11 — fixed in 3.3.11
- streetwriters notesnook: before 3.3.17 — fixed in 3.3.17
How to fix
Upgrade to a fixed version: streetwriters Notesnook Web/Desktop 3.3.11; streetwriters notesnook 3.3.17. Check the vendor advisory for mitigations.
References
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