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Vulnerability record · CVE-2026-42090 · published 4 May 2026

CVE-2026-42090: Streetwriters notesnook desktop cross-site scripting vulnerability

Streetwriters · Notesnook Desktop

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.

9.6 CVSS 3.1 Critical EPSS 0.85% · top 43.6% CWE-79 · Cross-site scriptingCWE-94 · Code injection
9.6CVSS 3.1 base score
0.85%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
3References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/streetwriters/notesnook/releases/tag/3.3.20-android Release Notes
https://github.com/streetwriters/notesnook/releases/tag/v3.3.15 Release Notes
https://github.com/streetwriters/notesnook/security/advisories/GHSA-fjm8-jg78-89h4 Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-42090), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.