CVE-2026-33976 Notesnook vulnerable to RCE via stored XSS in Web Clipper rendering
Attackers can achieve remote code execution in the Notesnook desktop app via stored XSS in the Web Clipper due to unsafe HTML rendering and Electron configuration.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-33976?
CVE-2026-33976 is a critical cross-site scripting vulnerability in streetwriters Notesnook Web/Desktop, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
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.
Which versions are affected by CVE-2026-33976?
It affects 2 products.
Products include Streetwriters Notesnook Desktop, Streetwriters Notesnook Mobile.
How do I fix CVE-2026-33976?
No fix has been published for CVE-2026-33976 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-33976 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33976 exists.
Other vulnerabilities in streetwriters Notesnook Web/Desktop
Sources
Also known as GHSA-f42f-phvp-43x5.