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Classification of calendar events is ignored by the activity stream (NC-SA-2019-001)

12th April 2019

Risk level: Low

CVSS v3 Base Score: 2.4 (AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:N/A:N)

CWE: Improper Authentication (CWE-287)

HackerOne report: 476615


A missing check revealed the name of confidential events and private events to all users of a shared calendar.

Affected Software

  • Nextcloud Server < 15.0.1 (CVE-2019-5449)
  • Nextcloud Server < 14.0.5 (CVE-2019-5449)
  • Nextcloud Server < 13.0.9 (CVE-2019-5449)

Action Taken

The error has been fixed.


It is recommended that all instances are upgraded to Nextcloud 15.0.1, 14.0.5 or 13.0.9.


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

  • Fabian Dellwing ( - Vulnerability discovery and disclosure.

This advisory is licensed CC BY-SA 4.0.

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