Cisco Cisco IOS Software Release 12.2

This vulnerability can be remotely triggered. A successful exploitation of this vulnerability may 
cause a reload of the device and could be exploited repeatedly to produce a Denial of Service (DoS). 

This advisory is available at 

CSCin68517

Symptoms: A Cisco router that is running Cisco Gateway GPRS Support Node (GGSN) software 
may show high CPU usage if deletion of a lot of PDP contexts is initiated from the GGSN side.

Conditions: Such deletion of a lot of PDPs from GGSN can be initiated from GGSN when the clear 
command is issued for all PDPs or all PDPs of a path/apn etc., or, if the update request is received 
on a path with a different restart count at a point when the path has lot of PDP contexts belonging 
to it.

Workaround: There is no workaround. 

CSCed93836

A vulnerability in the Transmission Control Protocol (TCP) specification (RFC793) has been 
discovered by an external researcher. The successful exploitation enables an adversary to reset any 
established TCP connection in a much shorter time than was previously discussed publicly. 
Depending on the application, the connection may get automatically re-established. In other cases, 
a user will have to repeat the action (for example, open a new Telnet or SSH session). Depending 
upon the attacked protocol, a successful attack may have additional consequences beyond 
terminated connection which must be considered. This attack vector is only applicable to the 
sessions which are terminating on a device (such as a router, switch, or computer) and not to the 
sessions that are only passing through the device (for example, transit traffic that is being routed by 
a router). In addition, this attack vector does not directly compromise data integrity or 
confidentiality. 

All Cisco products which contain TCP stack are susceptible to this vulnerability. 

This advisory is available at 

 and it describes this 

vulnerability as it applies to Cisco products that run Cisco IOS® software. 

A companion advisory that describes this vulnerability for products that do not run Cisco IOS 
software is available at 

Cisco IOS Release 12.2(21a) is a rebuild release for Cisco IOS Release 12.2(21). The caveats in this 
section are resolved in Cisco IOS Release 12.2(21a) but may be open in previous Cisco IOS releases.

The following information is provided for each caveat:

Symptoms: A description of what is observed when the caveat occurs. 

Conditions: The conditions under which the caveat has been known to occur. 

Workaround: Solutions, if available, to counteract the caveat.