(RHSA-2012:0126) Moderate: glibc security update

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.
(CVE-2009-5029)

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. (CVE-2009-5064)

An integer overflow flaw, leading to a heap-based buffer overflow, was
found in the way the glibc library loaded ELF (Executable and Linking
Format) 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. (CVE-2010-0830)

It was found that the glibc addmntent() function, used by various mount
helper utilities, did not handle certain errors correctly when updating the
mtab (mounted file systems table) file. If such utilities had the setuid
bit set, a local attacker could use this flaw to corrupt the mtab file.
(CVE-2011-1089)

A denial of service flaw was found in the remote procedure call (RPC)
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. (CVE-2011-4609)

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.

Users should upgrade to these updated packages, which resolve these issues.