CVE-2026-42090: streetwriters notesnook · Cross-site Scripting
Affects streetwriters notesnookSource CVE Database V5
Not known to be exploited · CVSS 9.6 Critical : upgrade to 3.3.15 as a priority.
Data as of 31 Oct 2026, 20:20 UTC
Contested
Critical score, yet low EPSS after six months- EPSS
- 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.3.15
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.
What to do
Upgrade streetwriters/notesnook to 3.3.15.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| streetwritersnotesnook | Affected
| Fixed in– |
GitHubstreetwriters/notesnookpkg:github/streetwriters/notesnookOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
This vulnerability has been patched in Notesnook Web/Desktop version 3.3.15 and Notesnook iOS/Android version 3.3.20. Users and administrators should upgrade to these or later versions to remediate the issue. Patch status is confirmed by the vendor advisory embedded in the description. No additional mitigations are indicated by the vendor.
Description
CVE-2026-42090 is a critical stored cross-site scripting (XSS) vulnerability in the Notesnook note-taking application affecting versions prior to 3.3.15 on Web/Desktop and prior to 3.3.20 on iOS/Android. The vulnerability arises because note fields such as title, headline, and content are inserted into an HTML template without proper HTML escaping during the note export flow. This allows malicious script injection that executes in a same-origin, unsandboxed iframe. In the desktop app, this escalates to remote code execution (RCE) due to Electron's insecure configuration (nodeIntegration: true, contextIsolation: false). The issue has been patched in the specified versions.