{"cve":"CVE-2025-66546","nvd":{"published":"2025-12-05T17:16:05.163","modified":"2026-10-18T14:10:00.110","status":"Analyzed","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","score":3.3},"cwes":["CWE-639"],"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"],"products":["nextcloud:calendar"],"source":"nvd","synced_at":"2026-10-19T22:16:40.427100871+00:00"},"epss":{"cve":"CVE-2025-66546","score":0.00139,"percentile":0.03211,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}