Vulnerability Report

CVE-2026-45281

Title: Calendar improper authorization

Auth Bypass

Proof Of Concept

No public PoC currently indexed for CVE-2026-45281.

CWE Category CWE-639
Published Date Jun 01, 2026
Modified Date Jun 03, 2026
Exploit Status Not Found
Score 8.1 CVSS v3.1
Exploit Probability (EPSS)
0.02%

Vulnerability Summary

CVE-2026-45281: 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

Impacted Vendors

N
nextcloud 1

Reference Links

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-hrrv-mp25-26vv https://github.com/nextcloud/server/pull/59962 https://hackerone.com/reports/3545964
CVSS v3.1
Source Entity [email protected]
Severity HIGH
8.1
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:H/I:H/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-45281 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

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:H/I:H/A:N

Affected Stack

No specific products linked.