CVE-2025-66550
Last modified
CVE-2025-66550 is a medium-severity vulnerability rated 5.7/10 on the CVSS scale. Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.17 and 5.2.4, when a malicious user creates a calendar event with a crafted attachment that links to a download link of a file on the same Nextcloud server, the file would be downloaded without the user confirming the action. EPSS estimates a 0.28% chance of exploitation in the next 30 days.
Description
Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.17 and 5.2.4, when a malicious user creates a calendar event with a crafted attachment that links to a download link of a file on the same Nextcloud server, the file would be downloaded without the user confirming the action. This vulnerability is fixed in 4.7.17 and 5.2.4.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Nextcloud | Calendar | >= 4.0.0, < 4.7.17 |
| Nextcloud | Calendar | >= 5.0.0, < 5.2.4 |
References
- https://github.com/nextcloud/calendar/pull/6971Issue Tracking
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f29c-ppmv-8mcvPatch, Vendor Advisory
- https://hackerone.com/reports/3112033Issue Tracking, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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