CVE-2025-66550: Nextcloud Calendar attachments of local files are offered to downloaded
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 Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2025-66550?
CVE-2025-66550 has been classified with a moderate severity due to its potential for unauthorized file downloads.
How do I fix CVE-2025-66550?
To fix CVE-2025-66550, upgrade your Nextcloud Calendar to versions 4.7.17 or 5.2.4 or later.
What versions of Nextcloud Calendar are affected by CVE-2025-66550?
CVE-2025-66550 affects Nextcloud Calendar versions prior to 4.7.17 and 5.2.4.
What kind of attack does CVE-2025-66550 involve?
CVE-2025-66550 involves a malicious user creating a calendar event with a crafted file attachment that prompts unauthorized downloads.
Is user confirmation required for downloads in CVE-2025-66550?
No, CVE-2025-66550 allows files to be downloaded without user confirmation, posing a security risk.