CVE-2025-66546

Nextcloud Calendar app allowed booking appointments without the generated token

CVSS 3.3 LOWEPSS 0.1%CWE-639

Vexday Risk Score

8Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 3.3EPSS 0.1%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

05 Dec 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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.

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

Affected products

nextcloud · security-advisories

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References

https://github.com/nextcloud/calendar/commit/f41650c3681fc4a4130eb883f5c0899c011326b3 https://github.com/nextcloud/calendar/pull/7537 https://github.com/nextcloud/security-advisories/security/advisories/GHSA-7x2j-2674-fj95 https://hackerone.com/reports/3275810