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. An integer overflow flaw, leading to a heap-based buffer overflow, was found in the way the glibc library read timezone files. If a carefully-crafted timezone file was loaded by an application linked against glibc, it could cause the application to crash or, potentially, execute arbitrary code with the privileges of the user running the application. 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 discovered that the glibc addmntent function, used by various mount helper utilities, did not sanitize its input properly. A local attacker could possibly use this flaw to inject malformed lines into the mtab file via certain setuid mount helpers, if the attacker were allowed to mount to an arbitrary directory under their control. An integer overflow flaw, leading to a heap-based buffer overflow, was found in the way the glibc library loaded ELF files. If a carefully-crafted ELF file was loaded by an application linked against glibc, it could cause the application to crash or, potentially, execute arbitrary code with the privileges of the user running the application. It was discovered that the glibc fnmatch function did not properly restrict the use of alloca. If the function was called on sufficiently large inputs, it could cause an application using fnmatch to crash or, possibly, execute arbitrary code with the privileges of the application. 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. It was discovered that the locale command did not produce properly escaped output as required by the POSIX specification. If an attacker were able to set the locale environment variables in the environment of a script that performed shell evaluation on the output of the locale command, and that script were run with different privileges than the attacker"s, it could execute arbitrary code with the privileges of the script. An integer overflow flaw was found in the glibc fnmatch function. If an attacker supplied a long UTF-8 string to an application linked against glibc, it could cause the application to crash. A denial of service flaw was found in the remote procedure call implementation in glibc. A remote attacker able to open a large number of connections to an RPC service that is using the RPC implementation from glibc, could use this flaw to make that service use an excessive amount of CPU time. Red Hat would like to thank the Ubuntu Security Team for reporting CVE-2010-0830, and Dan Rosenberg for reporting CVE-2011-1089. The Ubuntu Security Team acknowledges Dan Rosenberg as the original reporter of CVE-2010-0830. This update also fixes the following bug: * When using an nscd package that is a different version than the glibc package, the nscd service could fail to start. This update makes the nscd package require a specific glibc version to prevent this problem. Users should upgrade to these updated packages, which resolve these issues.