CVE-2026-31876: Streetwriters Notesnook Desktop

Medium severity, CVSS 5.4. EPSS: 0.2% chance of exploitation in the next 30 days.

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to 3.3.9, a Stored Cross-Site Scripting (XSS) vulnerability existed in Notesnook's editor embed component when rendering Twitter/X embed URLs. The tweetToEmbed() function in component.tsx interpolated the user-supplied URL directly into an HTML string without escaping, which was then assigned to the srcdoc attribute of an <iframe>. This vulnerability is fixed in 3.3.9.

Affected products

• Streetwriters Notesnook Desktop: before 3.3.9 (fixed in 3.3.9)
• Streetwriters Notesnook Mobile: before 3.3.15 (fixed in 3.3.15)

Published 2026-03-11. Last modified 2026-06-17.