Vulnerability · Published Dec 5, 2025 · Assigned by GitHub_M
CVE-2025-66546Nextcloud Calendar app allowed booking appointments without the generated token
Low 3.3
In plain English
A low-severity authorization bypass via user-controlled key in security-advisories from nextcloud. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 4% of all known vulnerabilities).
Severity (CVSS 3.1)3.3Low
Exploit odds (30 days)0.1%top 95.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| nextcloud | security-advisories | >= 6.0.0-rc.1, < 6.0.1>= 5.0.0-rc.1, < 5.5.6>= 3.0.0-beta1, < 4.7.19 |
Weakness: CWE-639 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
References
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-7x2j-2674-fj95 x_refsource_CONFIRM
- https://github.com/nextcloud/calendar/pull/7537 x_refsource_MISC
- https://github.com/nextcloud/calendar/commit/f41650c3681fc4a4130eb883f5c0899c011326b3 x_refsource_MISC
- https://hackerone.com/reports/3275810 x_refsource_MISC