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Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2025-66550

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
05/12/2025
Last modified:
10/12/2025

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

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N CVSS v3.1 Severity and Metrics:

Base Score: 5.70 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): Required
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): High
Availability (A): None

Base Score 3.x
5.70
Severity 3.x
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:* 4.0.0 (including) 4.7.17 (excluding)
cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:* 5.0.0 (including) 5.2.4 (excluding)

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools