CVE-2025-66550
Medium
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.
SeverityMedium
CVSS5.7
Exploit probability—
Product
Nextcloud Calendar
PublishedDec 5, 2025
First seenDec 5, 2025
Weakness typeCWE-241CWE-241
How to fix
Update
- nextcloud calendar4.7.17, 5.2.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| nextcloud calendar | 4.0.0 ≤ v < 4.7.17, 5.0.0 ≤ v < 5.2.4 | 4.7.17, 5.2.4 |
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