CVE-2026-42090: Notesnook is a note-taking app focused on user privacy & ease of use

Q: How do I fix CVE-2026-42090?

notesnook desktop: upgrade to 3.3.15; notesnook mobile: upgrade to 3.3.20; notesnook mobile: upgrade to 3.3.20. Exact commands for each OS are on this page.

Q: Is CVE-2026-42090 being exploited?

CVE-2026-42090 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-42090 affect?

CVE-2026-42090 affects notesnook desktop, notesnook mobile, notesnook mobile. Severity is critical (CVSS 9.6). Notesnook is a note-taking app focused on user privacy & ease of use. Prior to Notesnook Web/Desktop version 3.3.15 and prior to Notesnook iOS/Android version 3.3.20, a stored XSS vulnerability in the note export flow can be escalated to re

Q: How urgent is CVE-2026-42090?

Priority 44/100. Critical severity

This month

CRITICAL 9.6UPGRADEUPGRADEUPGRADE

CVE-2026-42090 is a critical-severity flaw (CVSS 9.6) affecting notesnook desktop, notesnook mobile, notesnook mobile. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to Notesnook Web/Desktop version 3.3.15 and prior to Notesnook iOS/Android version 3.3.20, a stored XSS vulnerability in the note export flow can be escalated to remote code execution in the desktop app. The root cause is that exported note fields such as title, headline, and content are inserted into the generated HTML template without HTML escaping. When the note is lat

Why this priority

Critical severity

A fixed release or distro patch exists.

Risk facts

CVSS score	9.6 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-79, CWE-94
Published	2026-05-04
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: streetwriters

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-04 17:16 UTCPublished CVE record published
2026-10-26 19:10 UTCUpdated Record last modified

streetwriters notesnook desktop UPGRADE

Affected: < 3.3.15

Fixed in: 3.3.15

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy notesnook-desktop || rpm -q notesnook-desktop || notesnook-desktop --version

2. UPGRADE to 3.3.15 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade notesnook-desktop

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade notesnook-desktop

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

streetwriters notesnook mobile UPGRADE

Affected: < 3.3.20

Fixed in: 3.3.20

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy notesnook-mobile || rpm -q notesnook-mobile || notesnook-mobile --version

2. UPGRADE to 3.3.20 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade notesnook-mobile

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade notesnook-mobile

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

streetwriters notesnook mobile UPGRADE

Affected: < 3.3.20

Fixed in: 3.3.20

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy notesnook-mobile || rpm -q notesnook-mobile || notesnook-mobile --version

2. UPGRADE to 3.3.20 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade notesnook-mobile

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade notesnook-mobile

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-42090?

notesnook desktop: upgrade to 3.3.15; notesnook mobile: upgrade to 3.3.20; notesnook mobile: upgrade to 3.3.20. Exact commands for each OS are on this page.

Is CVE-2026-42090 being exploited?

CVE-2026-42090 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-42090 affect?

CVE-2026-42090 affects notesnook desktop, notesnook mobile, notesnook mobile. Severity is critical (CVSS 9.6). Notesnook is a note-taking app focused on user privacy & ease of use. Prior to Notesnook Web/Desktop version 3.3.15 and prior to Notesnook iOS/Android version 3.3.20, a stored XSS vulnerability in the note export flow can be escalated to re

How urgent is CVE-2026-42090?

Priority 44/100. Critical severity

Software pages

Android vulnerabilities · iOS vulnerabilities

Related CVEs

CVE-2026-33976 CRITICAL 9.6 UPGRADE UPGRADE Notesnook is a note-taking app
CVE-2026-33955 HIGH 8.6 UPGRADE Notesnook is a note-taking app

References

← Back to latest CVEs