CVE-2026-45281 Details
Description
Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the attacker must be an authenticated user. This is because of improper authorization controls in the backend of the calendar. If the attacker had access to the calendar, they would be able to view and modify it. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, 29.0.16.16, 28.0.14.17, 27.1.11.26, 26.0.13.26, 25.0.13.29, 24.0.12.34, 23.0.12.35, 22.2.10.39, or 21.0.9.23
A vulnerability exists in Nextcloud Server versions 32.0.0 prior to 32.0.9 and 33.0.0 prior to 33.0.3, as well as in Nextcloud Enterprise Server versions 33.0.0 prior to 33.0.3 and several earlier versions. This vulnerability allows an authenticated user to exploit improper authorization controls in the calendar backend. By knowing another user's principal URL, an attacker could send a request to gain full access to that user's calendar, including the ability to view and modify calendar entries.
Users are advised to upgrade Nextcloud Server to version 33.0.3 or 32.0.9. Nextcloud Enterprise Server users should upgrade to version 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, 29.0.16.16, 28.0.14.17, 27.1.11.26, 26.0.13.26, 25.0.13.29, 24.0.12.34, 23.0.12.35, 22.2.10.39, or 21.0.9.23. If an immediate patch is not possible, access to the 'remote.php/dav/principals/users/<userid>/calendar-proxy-read' and 'remote.php/dav/principals/users/<userid>/calendar-proxy-write' endpoints should be blocked as a temporary measure.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jun 1, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/nextcloud/security-advisories/security/advisories/GHSA-hrrv-mp25-26vv | [email protected] | MitigationVendor Advisory |
| https://github.com/nextcloud/server/pull/59962 | [email protected] | Issue TrackingPatch |
| https://hackerone.com/reports/3545964 | [email protected] | Permissions Required |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-639 | Authorization Bypass Through User-Controlled Key | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| nextcloud nextcloud server | >= 32.0.0, < 32.0.9 >= 33.0.0, < 33.0.3 >= 21.0.0, < 21.0.9.23 >= 22.0.0, < 22.2.10.39 >= 23.0.0, < 23.0.12.35 >= 24.0.0, < 24.0.12.34 >= 25.0.0, < 25.0.13.29 >= 26.0.0, < 26.0.13.26 >= 27.0.0, < 27.1.11.26 >= 28.0.0, < 28.0.14.17 >= 29.0.0, < 29.0.16.16 >= 30.0.0, < 30.0.17.9 >= 31.0.0, < 31.0.14.5 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 22, 2026 | CVE Translated | [email protected] |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Jun 3, 2026 | Initial Analysis | [email protected] |
| Jun 1, 2026 | New CVE Received | [email protected] |