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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

PUBLISHED Reserved 2026-05-11 | Published 2026-06-01 | Updated 2026-06-01 | Assigner GitHub_M




HIGH: 8.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Problem types

CWE-639: Authorization Bypass Through User-Controlled Key

Product status

>= 32.0.0, < 32.0.9
affected

>= 33.0.0, < 33.0.3
affected

References

github.com/...sories/security/advisories/GHSA-hrrv-mp25-26vv

github.com/nextcloud/server/pull/59962

hackerone.com/reports/3545964

cve.org (CVE-2026-45281)

nvd.nist.gov (CVE-2026-45281)

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