CVE-2026-45286

Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint

Published Jun 1, 2026 CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Nextcloud
Nextcloud calendar
Vendors & Products Nextcloud
Nextcloud calendar
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint
Weaknesses CWE-200
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 1, 2026, 7:13 PM
Reserved
May 11, 2026, 8:14 PM
Status
Analyzed
Published
Jun 1, 2026, 7:16 PM
Modified
Jul 22, 2026, 8:10 AM