Multiple vulnerabilities has been found and corrected in glibc:

It was discovered that, under certain circumstances, glibc’s
getaddrinfo() function would send DNS queries to random file
descriptors. An attacker could potentially use this flaw to send DNS
queries to unintended recipients, resulting in information disclosure
or data loss due to the application encountering corrupted data
(CVE-2013-7423).

A buffer overflow flaw was found in the way glibc’s gethostbyname_r()
and other related functions computed the size of a buffer when passed
a misaligned buffer as input. An attacker able to make an application
call any of these functions with a misaligned buffer could use this
flaw to crash the application or, potentially, execute arbitrary
code with the permissions of the user running the application
(CVE-2015-1781).

The updated packages provides a solution for these security issues.