Cisco Catalyst CatOS Authentication Bypass Vulnerability



Date Discovered

April 24, 2003


A vulnerability has been reported for Cisco Catalyst switches that may result in unauthorized access to the enable level. The vulnerability exists due to the way the 'enable' mode is accessed through the switch. An attacker who is able to obtain command line access to a vulnerable switch is able to access 'enable' mode without a password.

Technologies Affected

  • Cisco Catalyst 4000 7.5.0 (1)
  • Cisco Catalyst 6000 7.5.0 (1)
  • Cisco Catalyst 6500 7.5.0 (1)


Block external access at the network boundary, unless external parties require service.
Configure the affected switch so that telnet/ssh connections are permitted from trusted hosts and networks only.

Permit privileged access for trusted individuals only.
Ensure that only trustworthy individuals are capable of connecting to vulnerable Catalyst Switches.

Implement multiple redundant layers of security.
The use of AAA configurations will prevent exploitation of this vulnerability. Ensure that AAA configurations are used and are not configured for fallback to local authentication.

This vulnerability is given the Cisco BugID of CSCea42030. This vulnerability does not affect Catalyst 4000, 6000 and 6500 switches running CatOS 7.6(1). Affected users are advised to contact Cisco to obtain fixes.



Discovery of this vulnerability credited to Marco P. Rodrigues.

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