RHSA-2015:1640 — Security Advisory

An updated pam package that fixes one security issue is now available for Red Hat Enterprise Linux 6 and 7.

Red Hat Product Security has rated this update as having Moderate security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

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

It was discovered that the _unix_run_helper_binary() function of PAM's unix_pam module could write to a blocking pipe, possibly causing the function to become unresponsive. An attacker able to supply large passwords to the unix_pam module could use this flaw to enumerate valid user accounts, or cause a denial of service on the system. (CVE-2015-3238)

Red Hat would like to thank Sebastien Macke of Trustwave SpiderLabs for reporting this issue.

All pam users are advised to upgrade to this updated package, which contains a backported patch to correct this issue.