Security Advisory

Back to advisories

User IDs and Nextcloud server leaked to Nextcloud Lookup server with disabled settings (NC-SA-2019-016)

26th June 2019

Risk level: Low

CVSS v3 Base Score: 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)

CWE: Exposure of Private Information (CWE-359)

HackerOne report: 508490


Exposure of Private Information in Nextcloud Server 16.0.1 causes the server to send it's domain and user IDs to the Nextcloud Lookup Server without any further data when the Lookup server is disabled.

Affected Software

  • Nextcloud Server < 16.0.2 (CVE-2019-15623)
  • Nextcloud Server < 15.0.9 (CVE-2019-15623)
  • Nextcloud Server < 14.0.13 (CVE-2019-15623)

Action Taken

The error has been fixed.


It is recommended that the Nextcloud Server is upgraded to 16.0.2.


The Nextcloud team thanks the following people for their research and responsible disclosure of the above advisory:

  • Leon Klingele - Vulnerability discovery and disclosure.

This advisory is licensed CC BY-SA 4.0.

You have javascript disabled. We tried to make sure the basics of our website work but some functionality will be missing.

This website is using cookies. By visiting you agree with our privacy policy. That's Fine