MGASA-2017-0224

It was possible to trigger an assertion by sending a malformed IPv6 packet. That issue could have been abused to remotely shutdown an openvpn server or client, if IPv6 and --mssfix were enabled and if the IPv6 networks used inside the VPN were known (CVE-2017-7508).

Some parts of the certificate-parsing code did not always clear all allocated memory. This would have allowed clients to leak a few bytes of memory for each connection attempt, thereby facilitating a (quite inefficient) DoS attack on the server (CVE-2017-7512).

If clients used a HTTP proxy with NTLM authentication, a man-in-the-middle attacker between client and proxy could cause the client to crash or disclose at most 96 bytes of stack memory. The disclosed stack memory was likely to contain the proxy password. If the proxy password had not been reused, this was unlikely to compromise the security of the OpenVPN tunnel itself. Clients who did not use the --http-proxy option with ntlm2 authentication were not affected (CVE-2017-7520).

The ASN1 parsing code contained a bug that could have resulted in some buffers being free()d twice, and this issue could have potentially been triggered remotely by a VPN peer (CVE-2017-7521).