Using the --fragment option in certain configuration setups OpenVPN version 2.6.0 to 2.6.6 allows an attacker to trigger a divide by zero behaviour which could cause an application crash, leading to a denial of service.
https://www.debian.org/security/2023/dsa-5555
https://openvpn.net/security-advisory/access-server-security-update-cve-2023-46849-cve-2023-46850/