Updated krb5 packages that fix multiple security issues are now available for CentOS Linux 2.1 and 3. This update has been rated as having critical security impact by the Red Hat Security Response Team.
Kerberos is a network authentication system which allows clients and servers to authenticate to each other through use of symmetric encryption and a trusted third party, the KDC. A flaw was found in the way the MIT Kerberos Authentication Service and Key Distribution Center server (krb5kdc) handled Kerberos v4 protocol packets. An unauthenticated remote attacker could use this flaw to crash the krb5kdc daemon, disclose portions of its memory, or possibly execute arbitrary code using malformed or truncated Kerberos v4 protocol requests. (CVE-2008-0062, CVE-2008-0063) This issue only affected krb5kdc with Kerberos v4 protocol compatibility enabled, which is the default setting on CentOS Linux 4. Kerberos v4 protocol support can be disabled by adding "v4_mode=none" (without the quotes) to the "[kdcdefaults]" section of /var/kerberos/krb5kdc/kdc.conf. A flaw was found in the RPC library used by the MIT Kerberos kadmind server. An unauthenticated remote attacker could use this flaw to crash kadmind. This issue only affected systems with certain resource limits configured and did not affect systems using default resource limits used by CentOS Linux 2.1 or 3. (CVE-2008-0948) CentOS would like to thank MIT for reporting these issues. All krb5 users are advised to update to these erratum packages which contain backported fixes to correct these issues.
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