Use of insufficiently random values in Nextcloud Calendar - CVE-2025-66511
Published: December 8, 2025
Vulnerability identifier: #VU119263
CSH Severity: Medium
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-66511
CWE-ID: CWE-330
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to compromise the target system.
The vulnerability exists due to the affected application generates participant tokens for meeting proposals using a hash function. A remote attacker can compute valid participant tokens and request details and submit dates in meeting proposals.
Affected software
Nextcloud Calendar
How to mitigate CVE-2025-66511
Install updates from vendor's website.
Nextcloud Calendar - update to 6.0.3