CVE-2025-66546
LOWCVSS 3.3/10EPSS 0.12%
Last modified
CVE-2025-66546 is a low-severity vulnerability rated 3.3/10 on the CVSS scale. 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. EPSS estimates a 0.12% chance of exploitation in the next 30 days.
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.
Metrics
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Nextcloud | Calendar | >= 4.0.0, < 4.7.19 |
| Nextcloud | Calendar | >= 5.0.0, < 5.5.6 |
| Nextcloud | Calendar | 6.0.0 |
References
- https://github.com/nextcloud/calendar/pull/7537Issue Tracking
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-7x2j-2674-fj95Patch, Vendor Advisory
- https://hackerone.com/reports/3275810Issue Tracking, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is 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 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.
How severe is CVE-2025-66546?
CVE-2025-66546 has a CVSS score of 3.3/10 (LOW severity). The EPSS model estimates a 0.12% probability of exploitation in the next 30 days.
How do I fix CVE-2025-66546?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
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Are you affected by CVE-2025-66546?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST