Vulnerability Note VU#787523

MIT Kerberos V5 KDC logging routines use unsafe format strings

Original Release date: 31 Jan 2003 | Last revised: 31 Jan 2003


Early releases of the MIT Kerberos V5 KDC contain format string vulnerabilities that can be used by unauthenticated remote attackers to conduct denial of service attacks on KDC servers.


Logging routines in some (unspecified) versions of the MIT Kerberos V5 Key Distribution Center (KDC) use Kerberos principal names as format strings for printf-style output functions. Principal names that contain certain printf format specifiers (such as '%n') may cause the KDC logging routines to read from or write to memory. Some vulnerable functions are called prior to authentication, therefore these vulnerabilities can be exploited by remote anonymous users. Note that vulnerabilities of this type may allow the execution of arbitrary code under certain circumstances.


This vulnerability may allow unauthenticated remote attackers to crash affected KDC processes, resulting in a denial of service condition.


This vulnerability was addressed in MIT Kerberos V5 1.2.5, released on April 30, 2002. MIT krb5 Security Advisory 2003-001 provides additional information from MIT and is available at:

For information regarding other vendors who may be affected, please see the vendor section of this document.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
MIT Kerberos Development TeamAffected20 May 200230 Jan 2003
Microsoft CorporationNot Affected29 Jul 200231 Jan 2003
KTH KerberosUnknown29 Jul 200229 Jan 2003
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



The CERT/CC thanks to E. Larry Lidz for discovering this vulnerability and Ken Raeburn of MIT for bringing it to our attention.

This document was written by Shawn Van Ittersum and Jeffrey P. Lanza.

Other Information

  • CVE IDs: CAN-2003-0060
  • Date Public: 28 Jan 2003
  • Date First Published: 31 Jan 2003
  • Date Last Updated: 31 Jan 2003
  • Severity Metric: 19.69
  • Document Revision: 24


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