CVE-2026-42090Public exploitNetwork attack vector

Code execution via unescaped note export fields

Published May 4, 2026 · Updated May 4, 2026

Stored XSS in Notesnook Web/Desktop before 3.3.15 allows remote attackers to execute code after a crafted note is exported to PDF. The export template inserts note-controlled title, headline, and content fields without HTML escaping, then loads the result into a same-origin, unsandboxed iframe with Node integration enabled. Exploitation requires attacker-controlled note data to enter the victim's account and the victim to export that note; successful desktop exploitation permits file access and command execution in the app's process context.

CVSS severity9.6
Critical
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Notesnook Web/Desktop before 3.3.15 allows remote attackers to execute code after a crafted note is exported to PDF. The export template inserts note-controlled title, headline, and content fields without HTML escaping, then loads the result into a same-origin, unsandboxed iframe with Node integration enabled. Exploitation requires attacker-controlled note data to enter the victim's account and the victim to export that note; successful desktop exploitation permits file access and command execution in the app's process context.

The record

CVE
CVE-2026-42090
Published
May 4, 2026
Updated
May 4, 2026
Vendor
Streetwriters
Product
Notesnook
Classifications
CWE-79, CWE-94, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 4, 2026CVE publishedPublication date reported by the CVE source.
  2. May 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Notesnook iOS/Android < 3.3.20
  2. Affected versionversion=Notesnook Web/Desktop < 3.3.15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Streetwriters · Notesnookversion=Notesnook iOS/Android < 3.3.20; version=Notesnook Web/Desktop < 3.3.15

Published CVSS scores

9.6GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-94Improper Control of Generation of Code ('Code Injection')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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