Vulnerability Note VU#898931

Multiple vendors' RADIUS implementations do not adequately validate user input thereby permitting DoS and arbitrary command execution via 'radiusd' daemon

Original Release date: 27 Jul 2001 | Last revised: 07 Aug 2001


Vulnerabilities in various implementations of the Remote Authentication Dial-In User Server (RADIUS) 'radiusd' daemon can allow an attacker to disrupt services or obtain unauthorized access.


Various implementations of the Remote Authentication Dial-In User Server (RADIUS) 'radiusd' daemon may contain buffer-overflow, format-string, and other vulnerabilities.

CERT/CC has identified three potential buffer-overflow vulnerabilities in Merit 3.6b RADIUS. These vulnerabilities stem from calls to strcpy() without enforcing buffer size limits when managing the user_realm, id, and name input variables. Version 3.6b1 corrects these vulnerabilities and improves bounds checking in the packet_log function to prevent more buffer overflows. Interlink Networks found additional vulnerabilities that were not resolved in 3.6b1, and they have corrected these in version 3.6b2.

Lucent 2.1-2 RADIUS was patched by Simon Horms to replace dozens of calls to strcpy(), sprintf(), and other functions that are often linked to buffer-overflow, format-string, and other vulnerabilities.

The Lucent and Merit RADIUS implementations are both derived from work at Livingston Enterprises. They have evolved independently into significantly different codebases, so vulnerabilities fixed in either implementation may not have been present in the other. Nevertheless, given the shared roots of the two products, any vulnerability found in one may be present in the other or in other derivative RADIUS products. We are working with other vendors to learn whether their RADIUS products have similar vulnerabilities that have not yet been announced.


Attackers who exploit these vulnerabilities may be able to interrupt RADIUS services or execute commands as the RADIUS user, which typically has administrator privileges. Loss or tampering of RADIUS services may prevent all access or allow unauthorized access to computer networks.


Apply patches available from your vendor.

Patches for the Lucent implementation are available at:

Merit offers patches to Merit RADIUS Server 3.6b1 at:

Interlink Networks offers its newer Merit RADIUS Server 3.6b2 at:

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
Interlink NetworksAffected16 Jul 200107 Aug 2001
Merit NetworksAffected12 Jul 200127 Jul 2001
Simon HormsAffected12 Jul 200127 Jul 2001
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



Thanks to Internet Security Systems X-Force for publishing an advisory on these vulnerabilities.

This document was written by Shawn Van Ittersum.

Other Information

  • CVE IDs: CAN-2001-0534
  • Date Public: 05 Jul 2001
  • Date First Published: 27 Jul 2001
  • Date Last Updated: 07 Aug 2001
  • Severity Metric: 20.11
  • Document Revision: 13


If you have feedback, comments, or additional information about this vulnerability, please send us email.