An issue was discovered in OpenVPN 2.4.x before 2.4.9. An attacker can inject a data channel v2 (P_DATA_V2) packet using a victim's peer-id. Normally such packets are dropped, but if this packet arrives before the data channel crypto parameters have been initialized, the victim's connection will be dropped. This requires careful timing due to the small time window (usually within a few seconds) between the victim client connection starting and the server PUSH_REPLY response back to the client. This attack will only work if Negotiable Cipher Parameters (NCP) is in use.

Affected: Ubuntu:18.04:LTS: openvpn, Ubuntu:20.04:LTS: openvpn

It was discovered that OpenVPN incorrectly handled certain data channel v2 packets. A remote attacker could possibly use this issue to inject packets using a victim's peer-id. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2020-11810)

It was discovered that OpenVPN incorrectly handled deferred authentication. When a server is configured to use deferred authentication, a remote attacker could possibly use this issue to bypass authentication and access control channel data. (CVE-2020-15078)