As per the upstream advisory:

By sending an invalid DTLS handshake to an OpenSSL DTLS client, the code can be made to recurse, eventually crashing in a DoS attack.

Only applications using OpenSSL as a DTLS client are affected.

OpenSSL 0.9.8 DTLS users should upgrade to 0.9.8za OpenSSL 1.0.0 DTLS users should upgrade to 1.0.0m. OpenSSL 1.0.1 DTLS users should upgrade to 1.0.1h. .

Acknowledgements:

Red Hat would like to thank the OpenSSL project for reporting this issue. Upstream acknowledges Imre Rad of Search-Lab as the original reporter of this issue.

As per the upstream advisory:

OpenSSL TLS clients enabling anonymous ECDH ciphersuites are subject to a denial of service attack.

OpenSSL 1.0.0 users should upgrade to 1.0.0m. OpenSSL 1.0.1 users should upgrade to 1.0.1h.

Acknowledgements:

Red Hat would like to thank the OpenSSL project for reporting this issue. Upstream acknowledges Felix Gröbert and Ivan Fratrić of Google as the original reporters of this issue.