Description
Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied to other endpoints, were not effective here. This issue has been patched in versions 5.5.17 and 6.2.3.
Affected products
nextcloud: calendar
References4
- github.com/nextcloud/security-advisories/security/advisories/GH… MitigationVendor Advisory
- github.com/nextcloud/calendar/issues/7971 ExploitIssue TrackingPatch
- github.com/nextcloud/calendar/pull/8197 Issue TrackingPatch
- hackerone.com/reports/3540663 Permissions Required
Metrics
- CVSS 3.1
-
4.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N - EPSS — exploit probability
- 0% percentile: 21 · as of 15 November 2026
- CWE
- CWE-200
Could this be exploited in your environment?
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