CVE-2025-66550
December 05, 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.
Affected Packages
https://github.com/nextcloud/calendar.git (GITHUB):
Affected version(s) >=v1.0 <v4.7.17Fix Suggestion:
Update to version v4.7.17https://github.com/nextcloud/calendar.git (GITHUB):
Affected version(s) >=v5.0.0 <v5.2.4Fix Suggestion:
Update to version v5.2.4Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
PASSIVE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.7
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Improper Handling of Unexpected Data Type
EPSS
Base Score:
0.03
