Uočene su tri sigurnosne ranjivosti u radu programskog paketa krb5. Udaljeni ih napadač može iskoristiti za izvođenje DoS (eng. Denial of Service) napada.

==========================================================================
Ubuntu Security Notice USN-1233-1
October 18, 2011

krb5 vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 11.10
- Ubuntu 11.04
- Ubuntu 10.10
- Ubuntu 10.04 LTS

Summary:

Several denial of service issues were fixed in the Kerberos Key
Distribution Center (KDC).

Software Description:
- krb5: MIT Kerberos Network Authentication Protocol

Details:

Nalin Dahyabhai, Andrej Ota and Kyle Moffett discovered a NULL
pointer dereference in the KDC LDAP backend. An unauthenticated
remote attacker could use this to cause a denial of service. This
issue affected Ubuntu 11.10. (CVE-2011-1527)

Mark Deneen discovered that an assert() could be triggered in the
krb5_ldap_lockout_audit() function in the KDC LDAP backend and
the krb5_db2_lockout_audit() function in the KDC DB2 backend. An
unauthenticated remote attacker could use this to cause a denial of
service. (CVE-2011-1528)

It was discovered that a NULL pointer dereference could occur in the
lookup_lockout_policy() function in the KDC LDAP and DB2 backends.
An unauthenticated remote attacker could use this to cause a denial of
service. (CVE-2011-1529)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 11.10:
  krb5-kdc                        1.9.1+dfsg-1ubuntu1.1
  krb5-kdc-ldap                   1.9.1+dfsg-1ubuntu1.1

Ubuntu 11.04:
  krb5-kdc                        1.8.3+dfsg-5ubuntu2.2
  krb5-kdc-ldap                   1.8.3+dfsg-5ubuntu2.2

Ubuntu 10.10:
  krb5-kdc                        1.8.1+dfsg-5ubuntu0.8
  krb5-kdc-ldap                   1.8.1+dfsg-5ubuntu0.8

Ubuntu 10.04 LTS:
  krb5-kdc                        1.8.1+dfsg-2ubuntu0.10
  krb5-kdc-ldap                   1.8.1+dfsg-2ubuntu0.10

In general, a standard system update will make all the necessary changes.

References:
  http://www.ubuntu.com/usn/usn-1233-1
  CVE-2011-1527, CVE-2011-1528, CVE-2011-1529

Package Information:
  https://launchpad.net/ubuntu/+source/krb5/1.9.1+dfsg-1ubuntu1.1
  https://launchpad.net/ubuntu/+source/krb5/1.8.3+dfsg-5ubuntu2.2
  https://launchpad.net/ubuntu/+source/krb5/1.8.1+dfsg-5ubuntu0.8
  https://launchpad.net/ubuntu/+source/krb5/1.8.1+dfsg-2ubuntu0.10