The glibc packages provide the standard C libraries (libc), POSIX threadlibraries (libpthread), standard math libraries (libm), and the NameServer Caching Daemon (nscd) used by multiple programs on the system.Without these libraries, the Linux system cannot function correctly.It was discovered that the nss_files backend for the Name Service Switch inglibc would return incorrect data to applications or corrupt the heap(depending on adjacent heap contents). A local attacker could potentiallyuse this flaw to execute arbitrary code on the system. (CVE-2015-5277)It was discovered that, under certain circumstances, glibc's getaddrinfo()function would send DNS queries to random file descriptors. An attackercould potentially use this flaw to send DNS queries to unintendedrecipients, resulting in information disclosure or data loss due to theapplication encountering corrupted data. (CVE-2013-7423)A buffer overflow flaw was found in the way glibc's gethostbyname_r() andother related functions computed the size of a buffer when passed amisaligned buffer as input. An attacker able to make an application callany of these functions with a misaligned buffer could use this flaw tocrash the application or, potentially, execute arbitrary code with thepermissions of the user running the application. (CVE-2015-1781)A heap-based buffer overflow flaw and a stack overflow flaw were found inglibc's swscanf() function. An attacker able to make an application callthe swscanf() function could use these flaws to crash that application or,potentially, execute arbitrary code with the permissions of the userrunning the application. (CVE-2015-1472, CVE-2015-1473)The CVE-2015-5277 issue was discovered by Sumit Bose and Lukáš Slebodník ofRed Hat, and the CVE-2015-1781 issue was discovered by Arjun Shankar of RedHat.All glibc users are advised to upgrade to these updated packages, whichcontain backported patches to correct these issues.