(RHSA-2013:0521) Moderate: pam security, bug fix, and enhancement update

Pluggable Authentication Modules (PAM) provide a system whereby
administrators can set up authentication policies without having to
recompile programs to handle authentication.

A stack-based buffer overflow flaw was found in the way the pam_env module
parsed users’ “~/.pam_environment” files. If an application’s PAM
configuration contained “user_readenv=1” (this is not the default), a
local attacker could use this flaw to crash the application or, possibly,
escalate their privileges. (CVE-2011-3148)

A denial of service flaw was found in the way the pam_env module expanded
certain environment variables. If an application’s PAM configuration
contained “user_readenv=1” (this is not the default), a local attacker
could use this flaw to cause the application to enter an infinite loop.
(CVE-2011-3149)

Red Hat would like to thank Kees Cook of the Google ChromeOS Team for
reporting the CVE-2011-3148 and CVE-2011-3149 issues.

These updated pam packages include numerous bug fixes and enhancements.
Space precludes documenting all of these changes in this advisory. Users
are directed to the Red Hat Enterprise Linux 6.4 Technical Notes, linked
to in the References, for information on the most significant of these
changes.

All pam users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues and add these
enhancements.