Cisco Cisco IOS Software Release 12.4(23) Notas de publicación

CSCef11304

Symptoms: When performing a snmpwalk on OSPF-MIB that supports the ospfExtLsdbTable, a 
router can crash. In other instances alignment errors are observed when you enter the show 
alignment command.

Conditions: These symptoms are observed on a Cisco platform that runs Open Shortest Path First 
(OSPF) and supports the ospfExtLsdbTable in OSPF-MIB.

Workaround: There is no workaround. 

CSCef33035

Symptoms: A router may crash and reload and generate the following error message:

TLB (load or instruction fetch) exception, CPU signal 10, PC = 0x609EE524

Conditions: This symptom is observed on a router that runs OSPF and that is configured with 
incremental SPF (ISPF).

Workaround: Disable ISPF by entering the no ispf router configuration command. 

CSCef60452

Symptoms: A router may stop receiving multicast traffic.

Conditions: This symptom is observed rarely during convergence when a router receives a Join 
message on an RPF interface and when a downstream router converges faster than the first router 
that receives the Join message.

In this situation, the router does not populate the RPF interface into the OIL (that is, the OIL remains 
null) because the old SP-tree has already been pruned by the downstream router. When the RPF 
interface of the router changes to the new path later, it does not trigger a Join message toward the 
multicast source until the router receives a next periodic Join message from the downstream router 
and populates the OIL. As a result, multicast traffic stops temporarily but no longer than the periodic 
Join message interval.

Workaround: There is no workaround. 

CSCef60659

A document that describes how the Internet Control Message Protocol (ICMP) could be used to 
perform a number of Denial of Service (DoS) attacks against the Transmission Control Protocol 
(TCP) has been made publicly available. This document has been published through the Internet 
Engineering Task Force (IETF) Internet Draft process, and is entitled “ICMP Attacks Against TCP” 
(draft-gont-tcpm-icmp-attacks-03.txt).

These attacks, which only affect sessions terminating or originating on a device itself, can be of 
three types:

Attacks that use ICMP “hard” error messages 

Attacks that use ICMP “fragmentation needed and Don’t Fragment (DF) bit set” messages, also 
known as Path Maximum Transmission Unit Discovery (PMTUD) attacks 

Attacks that use ICMP “source quench” messages

Successful attacks may cause connection resets or reduction of throughput in existing connections, 
depending on the attack type.

Multiple Cisco products are affected by the attacks described in this Internet draft.

Cisco has made free software available to address these vulnerabilities. In some cases there are 
workarounds available to mitigate the effects of the vulnerability.