Cisco Cisco IOS Software Release 12.2

CSCed28873

Cisco products running IOS contain vulnerabilities in the processing of H.323 messages, which are 
typically used in packetized voice or multimedia applications. Features such as NAT and IOS 
Firewall must inspect H.323 messages and may be vulnerable as well. A test suite has been 
developed by the University of Oulu to target this protocol and identify vulnerabilities. 

Support for the H.323 protocol was introduced in Cisco IOS Software Release 11.3T, and all later 
Cisco IOS releases are affected if configured for various types of Voice/Multimedia Application 
support. The vulnerabilities can be exploited repeatedly to produce a denial of service (DoS).

There are workarounds available that may mitigate the impact, but these techniques may not be 
appropriate for use in all customer networks.

This advisory is available at 

.

CSCed38527

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(19a) is a rebuild release for Cisco IOS Release 12.2(19). The caveats in this 
section are resolved in Cisco IOS Release 12.2(19a) 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.