Amazon Linux AMI Security Advisory: ALAS-2016-667
Advisory Release Date: 2016-03-10 16:30 Pacific
A heap-based buffer overflow flaw was found in the way NSS parsed certain ASN.1 structures. An attacker could use this flaw to create a specially crafted certificate which, when parsed by NSS, could cause it to crash, or execute arbitrary code, using the permissions of the user running an application compiled against the NSS library.
Run yum update nss-util to update your system.