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CERT Coordination Center

Cisco ASA fails to properly process DHCP relay packets

Vulnerability Note VU#530057

Original Release Date: 2007-05-02 | Last Revised: 2007-05-03


The Cisco Adaptive Security Appliance contains a memory exhaustion vulnerability that may occur when the DHCP service relay is enabled.


The Cisco Adaptive Security Appliance (ASA) is firewall that includes routing and intrusion prevention system (IPS) features. DHCP relay allows network devices to forward DHCP broadcast packets from a network segment that does not have a DHCP server to one that does. The Cisco ASA supports DHCP relay.

The Cisco ASA DHCP relay service contains a memory exhaustion vulnerability. An attacker may trigger the vulnerability by sending a large number of DHCP requests to a vulnerable system.


An unauthenticated attacker may be able to create a denial-of-service condition.


Cisco has released an update to address this issue. See Cisco BUG ID: CSCsh50277 for more details.

Increase DHCP lease times

Increasing the DHCP lease times may lengthen the amount of time required for an attacker to exhaust the available memory on a vulnerable system.

Vendor Information


Cisco Systems, Inc. Affected

Updated:  May 03, 2007



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


See for more details.

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

CVSS Metrics

Group Score Vector
Base 0 AV:--/AC:--/Au:--/C:--/I:--/A:--
Temporal 0 E:ND/RL:ND/RC:ND
Environmental 0 CDP:ND/TD:ND/CR:ND/IR:ND/AR:ND



This vulnerability was discovered by Lisa Sittler and Grant Deffenbaugh of CERT/CC.

This document was written by Ryan Giobbi.

Other Information

CVE IDs: None
Severity Metric: 0.64
Date Public: 2007-05-02
Date First Published: 2007-05-02
Date Last Updated: 2007-05-03 20:24 UTC
Document Revision: 29

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