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CVE-2026-42090

Streetwriters Notesnook Mobile remote code execution

9.6 CRITICALEPSS 0.85%
  1. Published4 May 2026

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 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected products

Streetwriters Notesnook Desktop< 3.3.15
Streetwriters Notesnook Mobile< 3.3.20

Remediation

Fixed in
Streetwriters Notesnook Desktop≥ 3.3.15
Streetwriters Notesnook Mobile≥ 3.3.20

References

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Frequently asked

Is CVE-2026-42090 being actively exploited?

CVE-2026-42090 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.85%.

How severe is CVE-2026-42090?

CVE-2026-42090 has a CVSS 3.1 base score of 9.6, rated critical. EPSS estimates a 0.85% probability of exploitation.

Which products are affected by CVE-2026-42090?

Affected products include Streetwriters Notesnook Desktop, Streetwriters Notesnook Mobile.

How do I fix CVE-2026-42090?

Upgrade affected software to a fixed version, for example Streetwriters Notesnook Desktop 3.3.15, Streetwriters Notesnook Mobile 3.3.20 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-42090 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.