The glibc packages provide the standard C libraries , POSIX thread libraries , standard math libraries , and the Name Server Caching Daemon used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly. 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. 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. A heap-based buffer overflow flaw and a stack overflow flaw were found in glibc"s swscanf function. An attacker able to make an application call the swscanf function could use these flaws to crash that application or, potentially, execute arbitrary code with the permissions of the user running the application. An integer overflow flaw, leading to a heap-based buffer overflow, was found in glibc"s _IO_wstr_overflow function. An attacker able to make an application call this function could use this flaw to crash that application or, potentially, execute arbitrary code with the permissions of the user running the application. A flaw was found in the way glibc"s fnmatch function processed certain malformed patterns. An attacker able to make an application call this function could use this flaw to crash that application. The CVE-2015-1781 issue was discovered by Arjun Shankar of Red Hat. These updated glibc packages also include numerous bug fixes and one enhancement. Space precludes documenting all of these changes in this advisory. For information on the most significant of these changes, users are directed to the following article on the Red Hat Customer Portal: https://access.redhat.com/articles/2050743 All glibc users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add these enhancements.