The pam_krb5 module allows Pluggable Authentication Modules (PAM) aware applications to use Kerberos to verify user identities by obtaining user credentials at log in time.
A flaw was found in the pam_krb5 "existing_ticket" configuration option. If a system is configured to use an existing credential cache via the "existing_ticket" option, it may be possible for a local user to gain elevated privileges by using a different, local user's credential cache. (CVE-2008-3825)
Red Hat would like to thank Stephane Bertin for responsibly disclosing this issue.
Users of pam_krb5 should upgrade to this updated package, which contains a backported patch to resolve this issue.