Amazon Linux AMI Security Advisory: ALAS-2016-651
Advisory Release Date: 2016-02-09 13:30 Pacific
A flaw was found in the way TLS 1.2 could use the MD5 hash function for signing ServerKeyExchange and Client Authentication packets during a TLS handshake. A man-in-the-middle attacker able to force a TLS connection to use the MD5 hash function could use this flaw to conduct collision attacks to impersonate a TLS server or an authenticated TLS client. (CVE-2015-7575 )
Run yum update gnutls to update your system.