CVE-2025-66546 json
Nextcloud Calendar app allowed booking appointments without the generated token
published 2025-12-05 11 mo ago modified 2026-10-18 21 d ago also EUVD-2025-201445
- cvss
- 3.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.1%
- EPSS 0.1% chance of exploitation in 30 days, percentile 4%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- nextcloud calendar 4.7.19, 5.5.6, 6.0.1
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 11 mo ago
Exploit prediction
0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 3.3 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N |
Affected products
- nextcloud security-advisories
Classification
- Weakness
-
- CWE-639 Authorization Bypass Through User-Controlled Key
References
-
github.com
/nextcloud/calendar/pull/7537
issue-tracking
-
github.com
/nextcloud/calendar/commit/f41650c3681fc4a4130eb883f5c0899c011326b3
patch
-
github.com
/nextcloud/security-advisories/security/advisories/GHSA-7x2j-2674-fj95
patch, vendor-advisory
-
hackerone.com
/reports/3275810
issue-tracking, vendor-advisory
Sources
- CVE List CVE-2025-66546
- NVD CVE-2025-66546
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.