RCE in Streetwriters Notesnook Desktop
CVE-2026-33976
Notesnook is a note-taking app. Prior to version 3.3.11 on Web/Desktop and 3.3.17 on Android/iOS, a stored XSS in the Web Clipper rendering flow can be escalated to remote code execution in the desktop app. The root cause is that the clipper preserves attacker-controlled attributes from the source page’s root element and stores them inside web-clip HTML. When the clip is later opened, Notesnook renders that HTML into a same-origin, unsandboxed iframe using `contentDocument.write(...)`. Event-handler attributes such as `onload`, `onclick`, or `onmouseover` execute in the Notesnook origin. In the desktop app, this becomes RCE because Electron is configured with `nodeIntegration: true` and `contextIsolation: false`. Version 3.3.11 Web/Desktop and 3.3.17 on Android/iOS patch the issue.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.6 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.007 (51.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: -0.000
Affected products
- Streetwriters Notesnook Desktop
- Streetwriters Notesnook Ios/android — versions < 3.3.17
- Streetwriters Notesnook Mobile
- Streetwriters Notesnook Web/desktop — versions < 3.3.11
Weakness classification (CWE)
References
- github.com/streetwriters/notesnook/security/advisories/GHSA-f42f-phvp-43x5 (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-33976?
- CVE-2026-33976 is a critical-severity vulnerability in Streetwriters Notesnook Desktop, classified under Cross-site Scripting. CVSS score: 9.6/10. Published 2026-03-27.
- How severe is CVE-2026-33976?
- Critical severity. CVSS v3 base score is 9.6 out of 10.