Medium · published December 5, 2025
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.
| Product | Versions | Fixed in |
|---|---|---|
| nextcloud/calendar | ≥ 4.0.0, < 4.7.17 | 4.7.17 |
| nextcloud/calendar | ≥ 5.0.0, < 5.2.4 | 5.2.4 |