CVE-2025-66546: Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.19, 5.5.6, and 6.0.1, the calendar app allowed…
CVE-2025-66546 · Severity: low · CVSS 3.3 · Published 2025-12-05
Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.19, 5.5.6, and 6.0.1, the calendar app allowed blindly booking appointments with a squential ID without known the appointment token. This vulnerability is fixed in 4.7.19, 5.5.6, and 6.0.1.
No. Junglewise Threat Intelligence has no report of CVE-2025-66546 being exploited in the wild.
How severe is CVE-2025-66546?
Low severity, with a CVSS score of 3.3, published 5 December 2025.
Which products and versions are affected?
Nextcloud Calendar. The advisory does not name versions.
Is there a fix for CVE-2025-66546?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2025-66546?
Check whether you run Nextcloud Calendar. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.