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CVE-2026-42090

9.6 · CRITICAL

Notesnook is a note-taking app focused on user privacy & ease of use.

Published May 4, 2026CWE-79EPSS 0.85%

Overview

CVE-2026-42090 is a critical-severity vulnerability. It was published on May 4, 2026 and has a CVSS 3.1 base score of 9.6 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.6, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/streetwriters/notesnook/releases/tag/3.3.20-androidGitHubgithub.com/streetwriters/notesnook/releases/tag/v3.3.15GitHubgithub.com/streetwriters/notesnook/security/advisories/GHSA-fjm8-jg78-89h4

How CyberStrike helps

Frequently asked questions

What is CVE-2026-42090?

CVE-2026-42090 is a critical-severity vulnerability. It was published on May 4, 2026 and has a CVSS 3.1 base score of 9.6 (CRITICAL).

How severe is CVE-2026-42090?

This vulnerability has a CVSS 3.1 base score of 9.6, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-42090?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-42090?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-42090 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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