RHSA-2016:0493 - Security Advisory

Topic

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

Red Hat Product Security 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 networked authentication system which allows clients and
servers to authenticate to each other with the help of a trusted third
party, the Kerberos KDC.

A memory leak flaw was found in the krb5_unparse_name() function of the MIT
Kerberos kadmind service. An authenticated attacker could repeatedly send
specially crafted requests to the server, which could cause the server to
consume large amounts of memory resources, ultimately leading to a denial
of service due to memory exhaustion. (CVE-2015-8631)

An out-of-bounds read flaw was found in the kadmind service of MIT
Kerberos. An authenticated attacker could send a maliciously crafted
message to force kadmind to read beyond the end of allocated memory, and
write the memory contents to the KDC database if the attacker has write
permission, leading to information disclosure. (CVE-2015-8629)

The CVE-2015-8631 issue was discovered by Simo Sorce of Red Hat.

All krb5 users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. After installing the
updated packages, running Kerberos services (krb5kdc, kadmin, and kprop)
will be restarted automatically.

Solution

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

For details on how to apply this update, refer to:

https://access.redhat.com/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 6.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.7 i386
• 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 6.7 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.7 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 for SAP Solutions for x86_64 - Extended Update Support 6.7 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 6.7 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.7 i386
• Red Hat Enterprise Linux EUS Compute Node 6.7 x86_64
• 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 - 1302617 - CVE-2015-8629 krb5: xdr_nullstring() doesn't check for terminating null character
• BZ - 1302642 - CVE-2015-8631 krb5: Memory leak caused by supplying a null principal name in request

CVEs

• CVE-2015-8629
• CVE-2015-8631

References

• https://access.redhat.com/security/updates/classification/#moderate