RHSA-2013:0656 - Security Advisory

Topic

Updated krb5 packages that fix two security issues are now available for
Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate
security impact. Common Vulnerability Scoring System (CVSS) base scores,
which give detailed severity ratings, are available for each vulnerability
from the CVE links in the References section.

Description

Kerberos is a network authentication system which allows clients and
servers to authenticate to each other using symmetric encryption and a
trusted third-party, the Key Distribution Center (KDC).

When a client attempts to use PKINIT to obtain credentials from the KDC,
the client can specify, using an issuer and serial number, which of the
KDC's possibly-many certificates the client has in its possession, as a
hint to the KDC that it should use the corresponding key to sign its
response. If that specification was malformed, the KDC could attempt to
dereference a NULL pointer and crash. (CVE-2013-1415)

When a client attempts to use PKINIT to obtain credentials from the KDC,
the client will typically format its request to conform to the
specification published in RFC 4556. For interoperability reasons, clients
and servers also provide support for an older, draft version of that
specification. If a client formatted its request to conform to this older
version of the specification, with a non-default key agreement option, it
could cause the KDC to attempt to dereference a NULL pointer and crash.
(CVE-2012-1016)

All krb5 users should upgrade to these updated packages, which contain
backported patches to correct these issues. After installing the updated
packages, the krb5kdc daemon will be restarted automatically.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/knowledge/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.4 i386
• Red Hat Enterprise Linux Server - AUS 6.4 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.4 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.4 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.4 x86_64
• Red Hat Gluster Storage Server for On-premise 2.1 x86_64
• Red Hat Storage for Public Cloud (via RHUI) 2.1 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.4 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• BZ - 914749 - CVE-2013-1415 krb5: PKINIT null pointer deref leads to DoS (pkinit_check_kdc_pkid())
• BZ - 917840 - CVE-2012-1016 krb5: PKINIT null pointer deref leads to DoS

CVEs

• CVE-2013-1415
• CVE-2012-1016

References

• https://access.redhat.com/security/updates/classification/#moderate
• http://tools.ietf.org/html/rfc4556