Cisco Cisco IOS Software Release 12.2(55)SE

CSCtc02635

On switches running Cisco IOS release 12.2(50)SE3 running MAC authentication bypass with 
multidomain authentication (MDA, IP phones connected to a port might not be able to regain 
network connectivity in the VOICE domain if the session times out and all RADIUS servers are 
unreachable.

There is no workaround.

CSCte14603

A vulnerability in the Internet Group Management Protocol (IGMP) version 3 implementation of 
Cisco IOS Software and Cisco IOS XE Software allows a remote unauthenticated attacker to cause 
a reload of an affected device. Repeated attempts to exploit this vulnerability could result in a 
sustained denial of service (DoS) condition. Cisco has released free software updates that address 
this vulnerability.

This advisory is posted at 

Note: The September 22, 2010, Cisco IOS Software Security Advisory bundled publication includes 
six Cisco Security Advisories. Five of the advisories address vulnerabilities in Cisco IOS Software, 
and one advisory addresses vulnerabilities in Cisco Unified Communications Manager. Each 
advisory lists the releases that correct the vulnerability or vulnerabilities detailed in the advisory. 
The table at the following URL lists releases that correct all Cisco IOS Software vulnerabilities that 
have been published on September 22, 2010, or earlier:

Individual publication links are in “Cisco Event Response: Semiannual Cisco IOS Software Security 
Advisory Bundled Publication” at the following link:

CSCtf19991

If the RADIUS authentication server is unavailable and inaccessible authentication bypass is 
enabled, the switch grants the client access to the network by putting the connected port in the 
critical-authentication state in the RADIUS-configured or the user-specified access VLAN. After 
the server is available, the client is not reinitalized and moved out of the critical VLAN.

There is no workaround.

CSCtf33948

A PC in 802.1x or multidomain authentication (MDA) mode is connected to an IP phone and 
connected to a MDA-enabled switch port. After the PC and phone are authenticated on the port, the 
PC is down. The port does not automatically reauthenticate the PC. 

There is no workaround.

CSCtf78276

A switch running Cisco IOS Release 12.2(53)SE1 stops when IEEE 802.1x authentication is 
enabled.

The workaround is to apply a VLAN that the RADIUS server assigned to the switch.

CSCtg26941

Multidomain authentication (MDA) with guest VLAN or MAC authentication bypass (MAB) as a 
fallback method is enabled on a switch running Cisco IOS Release 12.2(53)SE. When a non-802.1x 
client is connected to a IP phone and the phone connected to a switch port shuts down and then 
restarts, the client MAC address status is drop in the MAC address table. It takes 5 minutes for the 
client to access the network.