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CVE-2026-33978

Notesnook: Stored XSS in mobile share editor via unescaped web clip title metadata

5.4 Medium

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to version 3.3.17, a stored XSS vulnerability exists in the mobile share / web clip flow because attacker-controlled clip metadata is concatenated into HTML without escaping and then rendered with innerHTML inside the mobile share editor WebView. An attacker can control the shared title metadata (for example through Android/iOS share metadata such as TITLE / SUBJECT, or through link-preview title data) and inject HTML such as </a><img src=x onerror=...>. When the victim opens the Notesnook share flow and selects Web clip, the payload is inserted into the generated HTML and executed in the mobile editor WebView. This issue has been patched in version 3.3.17.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
None

Exploit likelihood

0.29%Up 0.3 points since Apr 2, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.4

Notesnook: Stored XSS in mobile share editor via unescaped web clip title metadata

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to version 3.3.17, a stored XSS vulnerability exists in the mobile share / web clip flow because attacker-controlled clip metadata is concatenated into HTML without escaping and then rendered with innerHTML inside the mobile share editor WebView. An attacker can control the shared title metadata (for example through Android/iOS share metadata such as TITLE / SUBJECT, or through link-preview title data) and inject HTML such as </a><img src=x onerror=...>. When the victim opens the Notesnook share flow and selects Web clip, the payload is inserted into the generated HTML and executed in the mobile editor WebView. This issue has been patched in version 3.3.17.

Record
CVE-2026-33978
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
EUVDEUVD-2026-17962 5.4

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to version 3.3.17, a stored XSS vulnerability exists in the mobile share / web clip flow because attacker-controlled clip metadata is concatenated into HTML without escaping and then rendered with innerHTML inside the mobile share editor WebView. An attacker can control the shared title metadata (for example through Android/iOS share metadata such as TITLE / SUBJECT, or through link-preview title data) and inject HTML such as </a><img src=x onerror=...>. When the victim opens the Notesnook share flow and selects Web clip, the payload is inserted into the generated HTML and executed in the mobile editor WebView. This issue has been patched in version 3.3.17.

Record
EUVD-2026-17962
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Updated
2026-11-02
NVD 5.4

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to version 3.3.17, a stored XSS vulnerability exists in the mobile share / web clip flow because attacker-controlled clip metadata is concatenated into HTML without escaping and then rendered with innerHTML inside the mobile share editor WebView. An attacker can control the shared title metadata (for example through Android/iOS share metadata such as TITLE / SUBJECT, or through link-preview title data) and inject HTML such as </a><img src=x onerror=...>. When the victim opens the Notesnook share flow and selects Web clip, the payload is inserted into the generated HTML and executed in the mobile editor WebView. This issue has been patched in version 3.3.17.

Record
CVE-2026-33978
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
OSV 5.4

Notesnook: Stored XSS in mobile share editor via unescaped web clip title metadata

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to version 3.3.17, a stored XSS vulnerability exists in the mobile share / web clip flow because attacker-controlled clip metadata is concatenated into HTML without escaping and then rendered with innerHTML inside the mobile share editor WebView. An attacker can control the shared title metadata (for example through Android/iOS share metadata such as TITLE / SUBJECT, or through link-preview title data) and inject HTML such as </a><img src=x onerror=...>. When the victim opens the Notesnook share flow and selects Web clip, the payload is inserted into the generated HTML and executed in the mobile editor WebView. This issue has been patched in version 3.3.17.

Record
CVE-2026-33978
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-33978 is a medium vulnerability (CVSS 5.4) in Streetwriters Notesnook, published April 1, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.29%, the 21st percentile. No source names a fixed version.

References

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