Cisco Cisco IOS Software Release 12.4(23)

Signaling protocols H.323, H.254 

Real-time Transport Protocol (RTP) 

Facsimile reception 

Cisco has made free software available to address these vulnerabilities for affected customers. Fixed 
Cisco IOS software listed in the Software Versions and Fixes section contains fixes for all 
vulnerabilities mentioned in this advisory.

There are no workarounds available to mitigate the effects of any of the vulnerabilities apart from 
disabling the protocol or feature itself. 

This advisory is posted at 

CSCuk56944

Symptoms: A router crashes when you remove X.25 WAN encapsulation from an interface that is 
configured for TCP header compression.

Conditions: This symptom is observed on a Cisco router that run Cisco IOS interim 
Release 12.4(0.4).

Workaround: Remove TCP header compression before you change the WAN encapsulation, as in the 
following example:

router(config)#int ser3/0

router(config-if)#no x25 map compressedtcp 10.10.10.11 170091

router(config-if)#no ip add

router(config-if)#no ip address

router(config-if)#encap frame

router(config-if)#encap frame-relay

CSCsa62111

Symptoms: Packets may be stuck in the input queue of a Cisco 7200 series.

Conditions: This symptom is observed on a Cisco 7200 series that is running Cisco IOS interim 
Release 12.3(12.10) and that is configured with an NPE-G1.

Workaround: Reload the router to clear the input queue or increase the input queue beyond the 
default limit of 75 via the hold-queue length command. 

CSCea75722

Symptoms: A Cisco IOS voice gateway may fail to receive a call from the public switched telephone 
network (PSTN) on its PRI port.

Conditions: This symptom is observed on a Cisco 2651XM that runs Cisco IOS Release 12.2(13)T3 
or Release 12.3 and that functions as a voice gateway when it does not send a Q.931 Call Proceeding 
message upon receiving the call.

Workaround: There is no workaround.