CVE-2025-66550 - CVE House
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Status published Medium CVE-2025-66550

Nextcloud Calendar attachments of local files are offered to downloaded

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

References

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Affected Vendor

Affected Software

security-advisories
Vulnerable Versions:
>= 5.0.0-rc.1, < 5.2.4, < 4.7.17

Timeline

Official Publish: December 5th, 2025
Last Modified: December 5th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N

Weaknesses (CWE)

CWE-241

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.