Cisco Cisco IOS Software Release 12.4(23)

Conditions: This symptom is observed when you enter the no isdn spoofing command and reload 
the router.

Workaround: Disable the no isdn spoofing command.

Cisco IOS Release 12.4(3e) is a rebuild release for Cisco IOS Release 12.4(3). The caveats in this 
section are resolved in Cisco IOS Release 12.4(3e) but may be open in previous Cisco IOS releases. 

CSCef29090

Symptoms: The throughput for TCPClear sessions on a Cisco AS5850 may not be as expected and 
there may be a slow response time.

Conditions: This symptom is observed on a Cisco AS5850 with TCPclear sessions.

Workaround: There is no workaround.

CSCek37177

The Cisco IOS Transmission Control Protocol (TCP) listener in certain versions of Cisco IOS 
software is vulnerable to a remotely-exploitable memory leak that may lead to a denial of service 
condition. 

This vulnerability only applies to traffic destined to the Cisco IOS device. Traffic transiting the 
Cisco IOS device will not trigger this vulnerability. 

Cisco has made free software available to address this vulnerability for affected customers. 

This issue is documented as Cisco bug ID 

CSCek37177

.

There are workarounds available to mitigate the effects of the vulnerability. 

This advisory is posted at 

CSCek38136

Symptoms: When you deploy VoIP using PVDM2 / 5510 DSP modules, a hissing sound may be 
heard before the ringback tone starts on the calling side.

Conditions: This symptom is observed only with 5510 DSP modules. The symptom does not occur 
with 549 DSP modules.

Workaround: There is no workaround. 

CSCsc03569

Symptoms: Incoming and outgoing PSTN calls fail on a BRI interface.

Conditions: This symptom has been observed on a Cisco 2620XM VoIP Gateway (MGCP) with 
Cisco IOS Release 12.4(2)T1 and a BRI Backhauled MGCP Gateway controlled by Cisco 
CallManager release 4.1(3)SR1.

Workaround: There is no workaround. 

CSCsc12255

Symptoms: When you deploy VoIP on an NM-HDV2 network module that is configured with a 
PVDM2-64 module, a hissing sound may be heard before the ringback tone starts on the calling side.

Conditions: This symptom is observed only with an NM-HDV2 network module. Note that the 
symptom does not occur with an NM-HDV network module.