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CVE-2026-42090: Notesnook Note Export Can Execute Malicious Code

CVE-2026-42090

Summary

Notesnook's note export feature had a security flaw that allowed attackers to execute malicious code on users' computers. This issue has been fixed in versions 3.3.15 and 3.3.20 of the desktop app and mobile apps, respectively. Users should update to the latest version to protect themselves.

Original title

Original description

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to Notesnook Web/Desktop version 3.3.15 and prior to Notesnook iOS/Android version 3.3.20, a stored XSS vulnerability in the note export flow can be escalated to remote code execution in the desktop app. The root cause is that exported note fields such as title, headline, and content are inserted into the generated HTML template without HTML escaping. When the note is later exported to PDF, Notesnook renders that HTML into a same-origin, unsandboxed iframe using iframe.srcdoc = .... Injected script executes in the Notesnook origin. In the desktop app, this becomes RCE because Electron is configured with nodeIntegration: true and contextIsolation: false. This issue has been patched in Notesnook Web/Desktop version 3.3.15 and Notesnook iOS/Android version 3.3.20.

nvd CVSS3.1 9.6

Vulnerability type

CWE-79 Cross-site Scripting (XSS)

CWE-94 Code Injection

Published: 4 May 2026 · Updated: 28 May 2026 · First seen: 4 May 2026