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Notesnook DesktopApplication · Streetwriters

CVE-2026-42090

CRITICAL · 9.6 CVSS v3.1 Published 2026-05-04
Fix available
A fix is available. Upgrade to 3.3.15 / 3.3.20 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A stored XSS vulnerability exists in Notesnook's note export flow where note fields (title, headline, content) are inserted into generated HTML templates without proper HTML escaping. When notes are exported to PDF, the unsanitized HTML is rendered in a same-origin, unsandboxed iframe via iframe.srcdoc, causing script execution. In the Electron desktop app, this escalates to RCE because nodeIntegration is enabled and contextIsolation is disabled, allowing injected JavaScript to access Node.js APIs.

MitigationUpgrade Notesnook Web/Desktop to version 3.3.15 or later, and iOS/Android to version 3.3.20 or later. As a defensive measure, disable or restrict the note export feature until patching is complete.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Notesnook DesktopApplication
Affected:< 3.3.15
Notesnook MobileApplication
Affected:< 3.3.20

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Notesnook Desktop version
    Open the desktop app and navigate to Settings > About, or check the application metadata file (e.g., package.json or app metadata)
    Affected if The installed version is lower than 3.3.15
  2. Check installed Notesnook Mobile version
    Open the mobile app, go to Settings > About, or check the app store listing for the installed version
    Affected if The installed version is lower than 3.3.20 on iOS or Android
  3. Verify Electron security configuration in desktop app
    Inspect the main Electron process code or bundled resources for nodeIntegration: true and contextIsolation: false settings in the BrowserWindow configuration
    Affected if nodeIntegration is true AND contextIsolation is false in the Electron configuration (enables RCE escalation)
  4. Check if PDF export functionality is accessible
    Attempt to export a note to PDF through the export menu or API endpoint (typically /api/export/pdf)
    Affected if PDF export feature is available and functional in the environment
  5. Inspect exported PDF for unsandboxed iframe usage
    Examine the generated PDF HTML source or the webview/iframe rendering code for iframe.srcdoc without sandbox attribute
    Affected if The export flow uses iframe.srcdoc without the sandbox attribute for rendering PDF content

You are affected if you are running Notesnook Desktop below version 3.3.15 or Mobile below version 3.3.20 AND you use the PDF export feature, with the desktop app additionally having insecure Electron security settings.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.3.15 / 3.3.20 or later
Fixed in 3.3.153.3.20
Interim mitigation

Upgrade Notesnook Web/Desktop to version 3.3.15 or later, and iOS/Android to version 3.3.20 or later. As a defensive measure, disable or restrict the note export feature until patching is complete.

Recommended fix High confidence

Notesnook Desktop 3.3.15 / Notesnook Mobile 3.3.20

  1. Upgrade Notesnook Desktop to version 3.3.15 or later
  2. Upgrade Notesnook Mobile (iOS/Android) to version 3.3.20 or later

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Notesnook Desktop Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA4.0 h
40.0 hours of engineering $7,000
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42090 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data