Authorization bypass through user-controlled key in Nextcloud Calendar - CVE-2025-66546
Published: December 8, 2025
Vulnerability identifier: #VU119262
CSH Severity: Low
CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-66546
CWE-ID: CWE-639
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to compromise the target system.
The vulnerability exists due to the affected application allows booking appointments without the generated token. A local user can gain access to sensitive information on the system.
Affected software
Nextcloud Calendar
How to mitigate CVE-2025-66546
Install updates from vendor's website.
Nextcloud Calendar - addressed in versions 4.7.19, 5.5.6, 6.0.1