Vulnerability in Nextcloud Calendar
CVE-2025-66550
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…
EPSS: 0.003 (20.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N.
Affected products
- Nextcloud Calendar
- Nextcloud Security-advisories — versions >= 5.0.0-rc.1, < 5.2.4, < 4.7.17
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Patch, Vendor Advisory)
- security-advisories@github.com (x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Issue Tracking, Vendor Advisory)
Frequently asked questions
- What is CVE-2025-66550?
- CVE-2025-66550 is a medium-severity vulnerability in Nextcloud Calendar, classified under CWE-241. CVSS score: 5.7/10. Published 2025-12-05.
- How severe is CVE-2025-66550?
- Medium severity. CVSS v3 base score is 5.7 out of 10.