Red Hat Enterprise Linux 6: RHSA-2010:0891-01 Moderate: pam Security Issue

Pluggable Authentication Modules (PAM) provide a system whereby administrators can set up authentication policies without having to recompile programs that handle authentication.
It was discovered that the pam_namespace module executed the external script namespace.init with an unchanged environment inherited from an application calling PAM. In cases where such an environment was untrusted (for example, when pam_namespace was configured for setuid applications such as su or sudo), a local, unprivileged user could possibly use this flaw to escalate their privileges. (CVE-2010-3853)
It was discovered that the pam_env and pam_mail modules used root privileges while accessing user's files. A local, unprivileged user could use this flaw to obtain information, from the lines that have the KEY=VALUE format expected by pam_env, from an arbitrary file. Also, in certain configurations, a local, unprivileged user using a service for which the pam_mail module was configured for, could use this flaw to obtain limited information about files or directories that they do not have access to. (CVE-2010-3435)
Note: As part of the fix for CVE-2010-3435, this update changes the default value of pam_env's configuration option user_readenv to 0, causing the module to not read user's ~/.pam_environment configuration file by default, as reading it may introduce unexpected changes to the environment of the service using PAM, or PAM modules consulted after pam_env.
It was discovered that the pam_xauth module did not verify the return values of the setuid() and setgid() system calls. A local, unprivileged user could use this flaw to execute the xauth command with root privileges and make it read an arbitrary input file. (CVE-2010-3316)
Red Hat would like to thank Sebastian Krahmer of the SuSE Security Team for reporting the CVE-2010-3435 issue.
All pam users should upgrade to these updated packages, which contain backported patches to correct these issues.