CVE-2025-66550

MEDIUM5.7

Nextcloud Calendar attachments of local files are offered to downloaded

Published Dec 5, 2025

Modified 1 months ago

No fix available

Details

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.

References

WEBhttps://github.com/nextcloud/calendar/commit/63a6c398db01391eb9fd5297a0d4c3d6e614f769 WEBhttps://github.com/nextcloud/calendar/pull/6971 WEBhttps://github.com/nextcloud/security-advisories/security/advisories/GHSA-f29c-ppmv-8mcv WEBhttps://hackerone.com/reports/3112033 ADVISORYhttps://www.cve.org/CVERecord?id=CVE-2025-66550

CVSS Analysis

CVSS v3.1

5.7

Exploitability

Attack Vector

NetworkAV:N

Attack Complexity

LowAC:L

Privileges Required

LowPR:L

User Interaction

RequiredUI:R

Scope

UnchangedS:U

Impact

Confidentiality

NoneC:N

Integrity

HighI:H

Availability

NoneA:N

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

Weakness Type (CWE)

Other

CWE-241

Ecosystems

Timeline

PublishedDec 5, 2025

ModifiedDec 5, 2025