Updated glibc packages that fix one security issue and one bug are now available for Red Hat Enterprise Linux 5. The Red Hat Security Response Team has rated this update as having moderate security impact. A Common Vulnerability Scoring System base score, which gives a detailed severity rating, is available from the CVE link in the References section. 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. Multiple integer overflow flaws, leading to heap-based buffer overflows, were found in glibc's memory allocator functions . If an application used such a function, it could cause the application to crash or, potentially, execute arbitrary code with the privileges of the user running the application. This update also fixes the following bug: * Prior to this update, the size of the L3 cache in certain CPUs for SMP servers was not correctly detected. The incorrect cache size detection resulted in less than optimal performance for routines that used this information, including the memset function. To fix this bug, the cache size detection has been corrected and core routines including memset have their performance restored to expected levels. All glibc users are advised to upgrade to these updated packages, which contain backported patches to correct these issues.