CVE-2026-45286 MEDIUM

CVE-2026-45286: Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint

Vendor Nextcloud
Product security-advisories
Weakness CWE-200 · Info exposure
Published June 1, 2026
Last update June 1, 2026

CVSS base score

4.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality Low
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

June 1, 2026 CVE published
June 1, 2026 Record updated