The glibc packages contain the standard C libraries used by multiple programs on the system. These packages contain the standard C and the standard math libraries. Without these two libraries, a Linux system cannot function properly. A flaw was found in the way the ldd utility identified dynamically linked libraries. If an attacker could trick a user into running ldd on a malicious binary, it could result in arbitrary code execution with the privileges of the user running ldd. It was found that the glibc addmntent function, used by various mount helper utilities, did not handle certain errors correctly when updating the mtab file. If such utilities had the setuid bit set, a local attacker could use this flaw to corrupt the mtab file. Red Hat would like to thank Dan Rosenberg for reporting the CVE-2011-1089 issue. This update also fixes several bugs and adds various enhancements. Documentation for these bug fixes and enhancements will be available shortly from the Technical Notes document, linked to in the References section. Users are advised to upgrade to these updated glibc packages, which contain backported patches to resolve these issues and add these enhancements.