6.8 - RHSA-2016:0532

Problem Description:

An update for krb5 is now available for Red Hat Enterprise Linux 7.

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

2. Relevant releases/architectures:

Red Hat Enterprise Linux Client (v. 7) - x86_64 Red Hat Enterprise Linux Client Optional (v. 7) - x86_64 Red Hat Enterprise Linux ComputeNode (v. 7) - x86_64 Red Hat Enterprise Linux ComputeNode Optional (v. 7) - x86_64 Red Hat Enterprise Linux Server (v. 7) - ppc64, ppc64le, s390x, x86_64 Red Hat Enterprise Linux Workstation (v. 7) - x86_64

3. Description:

Kerberos is a network authentication system, which can improve the security of your network by eliminating the insecure practice of sending passwords over the network in unencrypted form. It allows clients and servers to authenticate to each other with the help of a trusted third party, the Kerberos key distribution center (KDC).

Security Fix(es):

* 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)

* A NULL pointer dereference flaw was found in the procedure used by the MIT Kerberos kadmind service to store policies: the kadm5_create_principal_3() and kadm5_modify_principal() function did not ensure that a policy was given when KADM5_POLICY was set. An authenticated attacker with permissions to modify the database could use this flaw to add or modify a principal with a policy set to NULL, causing the kadmind service to crash. (CVE-2015-8630)

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

4. Solution:

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing the updated packages, running Kerberos services (krb5kdc, kadmin, and kprop) will be restarted automatically.

5. Bugs fixed (https://bugzilla.redhat.com/):

1302617 - CVE-2015-8629 krb5: xdr_nullstring() doesn't check for terminating null character 1302632 - CVE-2015-8630 krb5: krb5 doesn't check for null policy when KADM5_POLICY is set in the mask 1302642 - CVE-2015-8631 krb5: Memory leak caused by supplying a null principal name in request