CESA-2003:052: krb5 security update

Description

Updated kerberos packages fix a number of vulnerabilities found in MIT Kerberos.

Kerberos is a network authentication system. The MIT Kerberos team released an advisory describing a number of vulnerabilities that affect the kerberos packages shipped by CentOS. An integer signedness error in the ASN.1 decoder before version 1.2.5 allows remote attackers to cause a denial of service via a large unsigned data element length, which is later used as a negative value. The Common Vulnerabilities and Exposures project has assigned the name CAN-2002-0036 to this issue. The Key Distribution Center (KDC) before version 1.2.5 allows remote, authenticated, attackers to cause a denial of service (crash) on KDCs within the same realm via a certain protocol request that: - causes a null pointer dereference (CAN-2003-0058). - causes the KDC to corrupt its heap (CAN-2003-0082). A vulnerability in Kerberos before version 1.2.3 allows users from one realm to impersonate users in other realms that have the same inter-realm keys (CAN-2003-0059). The MIT advisory for these issues also mentions format string vulnerabilities in the logging routines (CAN-2003-0060). Previous versions of the kerberos packages from CentOS already contain fixes for this issue. Vulnerabilities have been found in the implementation of support for triple-DES keys in the implementation of the Kerberos IV authentication protocol included in MIT Kerberos (CAN-2003-0139). Vulnerabilities have been found in the Kerberos IV authentication protocol which allow an attacker with knowledge of a cross-realm key that is shared with another realm to impersonate any principal in that realm to any service in that realm. This vulnerability can only be closed by disabling cross-realm authentication in Kerberos IV (CAN-2003-0138). Vulnerabilities have been found in the RPC library used by the kadmin service in Kerberos 5. A faulty length check in the RPC library exposes kadmind to an integer overflow which can be used to crash kadmind (CAN-2003-0028). All users of Kerberos are advised to upgrade to these errata packages, which disable cross-realm authentication by default for Kerberos IV and which contain backported patches to correct these issues.