CVE-2026-45281 (GCVE-0-2026-45281)

Vulnerability from cvelistv5 – Published: 2026-06-01 16:52 – Updated: 2026-06-01 19:22
VLAI?
Title
Nextcloud: Cross-Account Calendar Takeover via Unauthorized Group-Member-Set Update
Summary
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
Severity ?
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-639 - Authorization Bypass Through User-Controlled Key
Assigner
References
Impacted products
Vendor Product Version
nextcloud security-advisories Affected: >= 32.0.0, < 32.0.9
Affected: >= 33.0.0, < 33.0.3
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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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