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.
Published: 2025-12-05
Score: 5.7 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Wed, 10 Dec 2025 14:15:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*

Fri, 05 Dec 2025 21:00:00 +0000

Type Values Removed Values Added
First Time appeared Nextcloud
Nextcloud calendar
Vendors & Products Nextcloud
Nextcloud calendar

Fri, 05 Dec 2025 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 05 Dec 2025 17:15:00 +0000

Type Values Removed Values Added
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.
Title Nextcloud Calendar attachments of local files are offered to downloaded
Weaknesses CWE-241
References
Metrics cvssV3_1

{'score': 5.7, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N'}


Subscriptions

Nextcloud Calendar
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-12-05T18:41:24.347Z

Reserved: 2025-12-04T15:57:22.034Z

Link: CVE-2025-66550

cve-icon Vulnrichment

Updated: 2025-12-05T18:39:44.289Z

cve-icon NVD

Status : Analyzed

Published: 2025-12-05T17:16:05.500

Modified: 2025-12-10T14:13:30.870

Link: CVE-2025-66550

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2025-12-05T20:56:16Z

Weaknesses