Vulnerability Report

CVE-2026-45286

Title: User Enumeration in Nextcloud Calendar app

Information Disclosure

Proof Of Concept

No public PoC currently indexed for CVE-2026-45286.

CWE Category CWE-200

Published Date Jun 01, 2026

Modified Date Jun 03, 2026

Exploit Status Not Found

Score 4.3 CVSS v3.1

Exploit Probability (EPSS)

0.02%

Vulnerability Summary

CVE-2026-45286: 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.

Impacted Vendors

karen_stevenson 1

nextcloud 1

Reference Links

https://github.com/nextcloud/calendar/issues/7971 https://github.com/nextcloud/calendar/pull/8197 https://github.com/nextcloud/security-advisories/security/advisories/GHSA-r697-74m9-gvf2 https://hackerone.com/reports/3540663

CVSS v3.1

Source Entity [email protected]

Severity MEDIUM

4.3

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

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

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-45286 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

June 03, 2026 MODIFIED

Vulnerability data updated via NVD.

June 02, 2026 MODIFIED

Vulnerability data updated via NVD.

June 01, 2026 MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK

Complexity LOW

Privileges N/A

Interaction NONE

CVSS Vector String


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

Affected Stack

No specific products linked.