CVE-2025-66550 MEDIUM

CVE-2025-66550: Nextcloud Calendar attachments of local files are offered to downloaded

Vendor Nextcloud
Product security-advisories
Weakness CWE-241
Published December 5, 2025
Last update December 5, 2025
View on NVD All CVEs

CVSS base score

5.7/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction Required
Confidentiality None
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

December 5, 2025 CVE published
December 5, 2025 Record updated