Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-33976

Severity CVSS v4.0:
Pending analysis
Type:
CWE-79 Cross-Site Scripting (XSS)
Publication date:
27/03/2026
Last modified:
31/03/2026

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.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 9.60 CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope (S): Changed
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x
9.60
Severity 3.x
CRITICAL

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:streetwriters:notesnook_desktop:*:*:*:*:*:*:*:* 3.3.11 (excluding)
cpe:2.3:a:streetwriters:notesnook_mobile:*:*:*:*:*:android:*:* 3.3.17 (excluding)
cpe:2.3:a:streetwriters:notesnook_mobile:*:*:*:*:*:iphone_os:*:* 3.3.17 (excluding)

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools