CVE-2025-66550
Dec. 10, 2025, 2:13 p.m.
5.7
Medium
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.
Product(s) Impacted
| Vendor | Product | Versions |
|---|---|---|
| Nextcloud |
|
|
Weaknesses
Common security weaknesses mapped to this vulnerability.
CWE-241
Improper Handling of Unexpected Data Type
The product does not handle or incorrectly handles when a particular element is not the expected type, e.g. it expects a digit (0-9) but is provided with a letter (A-Z).
*CPE(s)
Affected systems and software identified for this CVE.
| Type | Vendor | Product | Version | Update | Edition | Language | Software Edition | Target Software | Target Hardware | Other Information |
|---|---|---|---|---|---|---|---|---|---|---|
| a | nextcloud | calendar | / | / | / | / | / | / | / | / |
| a | nextcloud | calendar | / | / | / | / | / | / | / | / |
Tags
CVSS Score
CVSS Data - 3.1
- Attack Vector: NETWORK
- Attack Complexity: LOW
- Privileges Required: LOW
- Scope: UNCHANGED
- Confidentiality Impact: NONE
- Integrity Impact: HIGH
- Availability Impact: NONE
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
Timeline
Published: Dec. 5, 2025, 5:16 p.m.
Last Modified: Dec. 10, 2025, 2:13 p.m.
Last Modified: Dec. 10, 2025, 2:13 p.m.
Status : Analyzed
CVE has had analysis completed and all data associations made.
More infoSource
security-advisories@github.com
*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.