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Cisco Security Advisory: IPv6 Crafted Packet Vulnerability



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Hash: SHA1

Cisco Security Advisory: IPv6 Crafted Packet Vulnerability

Revision 1.0

For Public Release 2005 July 29 0800 UTC

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-------------------------------------------------------------------------------

Contents
========

    Summary
    Affected Products
    Details
    Impact
    Software Versions and Fixes
    Obtaining Fixed Software
    Workarounds
    Exploitation and Public Announcements
    Status of This Notice: INTERIM
    Distribution
    Revision History
    Cisco Security Procedures

- --------------------------------------------------------------------------

Summary
=======

Cisco Internetwork Operating System (IOS ) Software is vulnerable to a Denial
of Service (DoS) and potentially an arbitrary code execution attack from a
specifically crafted IPv6 packet. The packet must be sent from a local network
segment. Only devices that have been explicitly configured to process IPv6
traffic are affected. Upon successful exploitation, the device may reload or be
open to further exploitation.

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

This advisory will be posted at 
http://www.cisco.com/warp/public/707/cisco-sa-20050729-ipv6.shtml.

Affected Products
=================

Vulnerable Products

This issue affects all Cisco devices running any unfixed version of Cisco IOS
code that supports, and is configured for, IPv6. A device which supports IPv6
must have the interfaces specifically disabled to not be affected. IPv6 must be
completely disabled using both the command no ipv6 address and no ipv6 enable
on each interface.

Sample output of the show ipv6 interface command is shown below for two
systems, one not configured for IPv6 and one configured for IPv6.

An empty output or an error message will be displayed if IPv6 is disabled or
unsupported on the system.

    Router#show ipv6 int fa 0/0

    -here you see blank output


In the example below the system is vulnerable.

    Router#show ipv6 interface
    Serial1/0 is up, line protocol is up
      IPv6 is enabled, link-local address is FE80::A8BB:CCFF:FE00:D200
      Global unicast address(es):
        2001:1:33::3, subnet is 2001:1:33::/64
      Joined group address(es):
        FF02::1
        FF02::1:FF00:3
        FF02::1:FF00:D200
      MTU is 1500 bytes
      ICMP error messages limited to one every 100 milliseconds
      ICMP redirects are enabled
      ND DAD is enabled, number of DAD attempts: 1
      ND reachable time is 30000 milliseconds
    Router#


A router that has IPv6 enabled on a physical or logical interface is vulnerable
to this issue even if ipv6 unicast-routing is globally disabled. The show ipv6
interface command can be used to determine whether IPv6 is enabled on any
interface.

To determine the software running on a Cisco product, log in to the device and
issue the show version command to display the system banner. Cisco IOS Software
will identify itself as "Internetwork Operating System Software" or simply
"IOS." On the next line of output, the image name will be displayed between
parentheses, followed by "Version" and the IOS release name. Other Cisco
devices will not have the show version command or will give different output.

The following example shows a product running IOS release 12.3(6) with an image
name of C2600-JS-MZ:

    Cisco Internetwork Operating System Software IOS (tm)

    C2600 Software (C2600-JS-MZ), Version 12.3(6), RELEASE SOFTWARE (fc1)


Additional information about Cisco IOS release naming can be found at http://
www.cisco.com/warp/public/620/1.html.

Products Confirmed Not Vulnerable

Products that are not running Cisco IOS are not affected.

Products running any version of Cisco IOS that do not have IPv6 configured
interfaces are not vulnerable.

No other Cisco products are currently known to be affected by these
vulnerabilities.

Details
=======

IPv6 is the "Internet Protocol Version 6", designed by the Internet Engineering
Task Force (IETF) to replace the current version Internet Protocol, IP Version
4 (IPv4).

A vulnerability exists in the processing of IPv6 packets. Crafted packets from
the local segment received on logical interfaces (that is, tunnels including
6to4 tunnels) as well as physical interfaces can trigger this vulnerability.
Crafted packets can not traverse a 6to4 tunnel and attack a box across the
tunnel.

The crafted packet must be sent from a local network segment to trigger the
attack. This vulnerability can not be exploited one or more hops from the IOS
device.

This issue is documented in Cisco bug ID CSCef68324.

Impact
======

Successful exploitation of the vulnerability may result in a reload of the
device or execution of arbitrary code. Repeated exploitation could result in a
sustained DoS attack or execution of arbitrary code.

Software Versions and Fixes
===========================

Each row of the Cisco IOS software table below describes a release train and
the platforms or products for which it is intended. If a given release train is
vulnerable, then the earliest possible releases that contain the fix (the First
Fixed Release) and the anticipated date of availability for each are listed in
the Rebuild and Maintenance columns. A device running a release in the given
train that is earlier than the release in a specific column (less than the
First Fixed Release) is known to be vulnerable. The release should be upgraded
at least to the indicated release or a later version (greater than or equal to
the First Fixed Release label).

+---------------------------------------------+
| Major Release  |  Availability of Repaired  |
|                |          Releases          |
|----------------+----------------------------|
|    Affected    |              |             |
|   12.0-Based   |   Rebuild    | Maintenance |
|    Release     |              |             |
|----------------+--------------+-------------|
| 12.0S          | 12.0(26)S6   |             |
|----------------+--------------+-------------|
|                | 12.0(27)S5   |             |
|----------------+--------------+-------------|
|                | 12.0(28)S3   |             |
|----------------+--------------+-------------|
|                | 12.0(30)S2   | 12.0(31)S   |
|----------------+----------------------------|
| 12.0SX         | Vulnerable; contact TAC    |
|----------------+----------------------------|
|                | Vulnerable; migrate to     |
|                | 12.0(31)S or later         |
|----------------+----------------------------|
| 12.0SL         | Vulnerable; migrate to     |
|                | 12.0(31)S or later         |
|----------------+----------------------------|
| 12.0ST         | Vulnerable; migrate to     |
|                | 12.0(31)S or later         |
|----------------+----------------------------|
| 12.0SY         | Vulnerable; migrate to     |
|                | 12.0(31)S or later         |
|----------------+----------------------------|
|    Affected    |              |             |
|   12.1-Based   |   Rebuild    | Maintenance |
|    Release     |              |             |
|----------------+----------------------------|
| 12.1XU         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.1XV         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.1YB         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.1YC         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.1YD         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.1YE         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.1YF         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.1YH         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.1YI         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
|    Affected    |              |             |
|   12.2-Based   |   Rebuild    | Maintenance |
|    Release     |              |             |
|----------------+----------------------------|
| 12.2B          | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2BC         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2BW         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2BY         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2BX         | Vulnerable; migrate to     |
|                | 12.3(7)XI4 or later        |
|----------------+----------------------------|
| 12.2BZ         | Vulnerable; migrate to     |
|                | 12.3(7)XI4 or later        |
|----------------+----------------------------|
| 12.2CX         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2CY         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2CZ         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2DD         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2DX         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2EU         | 12.2(20)EU1  |             |
|----------------+----------------------------|
| 12.2EW         | Vulnerable; migrate to     |
|                | 12.2(25)EWA                |
|----------------+----------------------------|
| 12.2EWA        | 12.2(25)EWA1 |             |
|----------------+----------------------------|
| 12.2EX         | Vulnerable; migrate to     |
|                | 12.2(25)SEA or later       |
|----------------+----------------------------|
| 12.2EY         | 12.2(25)EY1  |             |
|----------------+--------------+-------------|
| 12.2EZ         |              | 12.2(25)EZ  |
|----------------+----------------------------|
| 12.2JA         | Vulnerable; migrate to     |
|                | 12.3(4)JA or later         |
|----------------+----------------------------|
| 12.2JK         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2MB         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2MC         | Vulnerable; migrate to     |
|                | 12.4(2)MR                  |
|----------------+----------------------------|
| 12.2MX         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
|                | 12.2(14)S14  |             |
|                |--------------+-------------|
|                | 12.2(18)S9   |             |
|12.2S           |--------------+-------------|
|                | 12.2(20)S8   |             |
|                |--------------+-------------|
|                | 12.2(25)S4   |             |
|----------------+----------------------------|
| 12.2SE         | Vulnerable; migrate to     |
|                | 12.2(25)SEB or later       |
|----------------+----------------------------|
| 12.2SEA        | Vulnerable; migrate to     |
|                | 12.2(25)SEB or later       |
|----------------+----------------------------|
| 12.2SEB        |              | 12.2(25)SEB |
|----------------+--------------+-------------|
| 12.2SEC        |              | 12.2(25)SEC |
|----------------+----------------------------|
| 12.2SO         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2SU         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2SV         |              | 12.2(26)SV  |
|----------------+----------------------------|
| 12.2SW         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2SX         | Vulnerable; migrate to     |
|                | 12.2(17d)SXB8 or later     |
|----------------+----------------------------|
| 12.2SXA        | Vulnerable; migrate to     |
|                | 12.2(17d)SXB8 or later     |
|----------------+----------------------------|
| 12.2SXB        | 12.2(17d)    |             |
|                | SXB8         |             |
|----------------+--------------+-------------|
| 12.2SXD        | 12.2(18)SXD4 |             |
|----------------+--------------+-------------|
| 12.2SXE        | 12.2(18)SXE1 |             |
|----------------+----------------------------|
| 12.2SY         | Vulnerable; migrate to     |
|                | 12.2(17d)SXB8 or later     |
|----------------+----------------------------|
| 12.2SZ         | Vulnerable; migrate to     |
|                | 12.2(20)S8 or later        |
|----------------+----------------------------|
|                | 12.2(13)T16  |             |
|12.2T           |--------------+-------------|
|                | 12.2(15)T16  |             |
|----------------+----------------------------|
| 12.2XA         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XB         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XC         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2XD         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XE         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XF         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2XG         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XH         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XI         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XJ         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XK         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XL         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XM         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XN         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XQ         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XR         | Vulnerable; migrate to     |
|                | 12.3(4)JA or later         |
|----------------+----------------------------|
| 12.2XT         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XU         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XW         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2XZ         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2YT         | Vulnerable; migrate to     |
|                | 12.2(15)T16 or later       |
|----------------+----------------------------|
| 12.2YU         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2YV         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2YZ         | Vulnerable; migrate to     |
|                | 12.2(20)S8 or later        |
|----------------+----------------------------|
| 12.2ZA         | Vulnerable; migrate to     |
|                | 12.2(17d)SXB8 or later     |
|----------------+----------------------------|
| 12.2ZC         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2ZD         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2ZE         | Vulnerable; migrate to     |
|                | 12.3(15) or later          |
|----------------+----------------------------|
| 12.2ZF         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2ZG         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2ZH         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2ZJ         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2ZL         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.2ZN         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.2ZO         | Vulnerable; migrate to     |
|                | 12.2(15)T16 or later       |
|----------------+----------------------------|
| 12.2ZP         | Vulnerable; contact TAC    |
|----------------+----------------------------|
|    Affected    |              |             |
|   12.3-Based   |   Rebuild    | Maintenance |
|    Release     |              |             |
|----------------+--------------+-------------|
|                | 12.3(3h)     |             |
|                |--------------+-------------|
|                | 12.3(5e)     |             |
|                |--------------+-------------|
|                | 12.3(6e)     |             |
|                |--------------+-------------|
| 12.3           | 12.3(9d)     |             |
|                |--------------+-------------|
|                | 12.3(10d)    |             |
|                |--------------+-------------|
|                | 12.3(12b)    |             |
|                |--------------+-------------|
|                | 12.3(13a)    | 12.3(15)    |
|----------------+--------------+-------------|
| 12.3B          | 12.3(5a)B5   |             |
|----------------+--------------+-------------|
| 12.3BC         |              | 12.3(13a)BC |
|----------------+----------------------------|
| 12.3BW         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.3JA         |              | 12.3(4)JA   |
|----------------+--------------+-------------|
| 12.3JK         |              | 12.3(2)JK   |
|----------------+--------------+-------------|
|                | 12.3(7)T9    |             |
|                |--------------+-------------|
|                | 12.3(8)T8    |             |
|12.3T           |--------------+-------------|
|                | 12.3(11)T5   |             |
|                |--------------+-------------|
|                | 12.3(14)T2   |             |
|----------------+----------------------------|
| 12.3XA         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3XB         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.3XC         | 12.3(2)XC3   |             |
|----------------+----------------------------|
| 12.3XD         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3XE         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3XF         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.3XG         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3XH         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.3XI         | 12.3(7)XI4   |             |
|----------------+----------------------------|
| 12.3XJ         | Vulnerable; migrate to     |
|                | 12.3(11)YF3 or later       |
|----------------+----------------------------|
| 12.3XK         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3XL         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3XM         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.3XQ         | 12.3(4)XQ1   |             |
|----------------+--------------+-------------|
| 12.3XR         | 12.3(7)XR4   |             |
|----------------+----------------------------|
| 12.3XS         | Vulnerable; migrate to     |
|                | 12.4(1) or later           |
|----------------+----------------------------|
| 12.3XT         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3XU         | Vulnerable; migrate to     |
|                | 12.4(2)T or later          |
|----------------+----------------------------|
| 12.3XW         | Vulnerable; migrate to     |
|                | 12.3(11)YF3 or later       |
|----------------+----------------------------|
| 12.3XX         | Vulnerable; migrate to     |
|                | 12.4(1) or later           |
|----------------+----------------------------|
| 12.3XY         | Vulnerable; migrate to     |
|                | fixed 12.3(14)T2 or later  |
|----------------+----------------------------|
| 12.3YA         | 12.3(8)YA1   |             |
|----------------+----------------------------|
| 12.3YD         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3YF         | 12.3(11)YF3  |             |
|----------------+--------------+-------------|
| 12.3YG         | 12.3(8)YG2   |             |
|----------------+----------------------------|
| 12.3YH         | Vulnerable; migrate to     |
|                | 12.3(8)YI1 or later        |
|----------------+----------------------------|
| 12.3YI         | 12.3(8)YI1   |             |
|----------------+--------------+-------------|
| 12.3YJ         | 12.3(11)YJ   |             |
|----------------+----------------------------|
| 12.3YK         | Vulnerable; contact TAC    |
|----------------+----------------------------|
| 12.3YQ         | 12.3(14)YQ1  |             |
|----------------+--------------+-------------|
| 12.3YS         |              | 12.3(11)YS  |
|----------------+--------------+-------------|
| 12.3YT         |              | 12.3(14)YT  |
|----------------+--------------+-------------|
| 12.3YU         |              | 12.3(14)YU  |
|----------------+--------------+-------------|
|    Affected    |              |             |
|   12.4-Based   |   Rebuild    | Maintenance |
|    Release     |              |             |
|----------------+--------------+-------------|
| 12.4           |              | 12.4(1)     |
|----------------+--------------+-------------|
| 12.4MR         |              | 12.4(2)MR   |
|----------------+--------------+-------------|
| 12.4T          |              | 12.4(2)T    |
+---------------------------------------------+

For further information on the terms "Rebuild" and "Maintenance, " please
consult the following URL: http://www.cisco.com/warp/public/620/1.html

When considering software upgrades, please also consult http://www.cisco.com/en
/US/products/products_security_advisories_listing.html and any subsequent
advisories to determine exposure and a complete upgrade solution.

In all cases, customers should exercise caution to be certain the devices to be
upgraded contain sufficient memory and that current hardware and software
configurations will continue to be supported properly by the new release. If
the information is not clear, contact the Cisco Technical Assistance Center
("TAC") for assistance.

Obtaining Fixed Software
========================

Customers with Service Contracts

Customers with contracts should obtain upgraded software through their regular
update channels. For most customers, this means that upgrades should be
obtained through the Software Center on Cisco's worldwide website at http://
www.cisco.com.

Customers using Third-party Support Organizations

Customers whose Cisco products are provided or maintained through prior or
existing agreement with third-party support organizations such as Cisco
Partners, authorized resellers, or service providers should contact that
support organization for assistance with the upgrade, which should be free of
charge.

Customers without Service Contracts

Customers who purchase direct from Cisco but who do not hold a Cisco service
contract and customers who purchase through third-party vendors but are
unsuccessful at obtaining fixed software through their point of sale should get
their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC
contacts are as follows.

  * +1 800 553 2447 (toll free from within North America)
  * +1 408 526 7209 (toll call from anywhere in the world)
  * e-mail: tac@xxxxxxxxx

Please have your product serial number available and give the URL of this
notice as evidence of your entitlement to a free upgrade. Free upgrades for
non-contract customers must be requested through the TAC.

Please do not contact either "psirt@xxxxxxxxx" or "security-alert@xxxxxxxxx"
for software upgrades.

See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional
TAC contact information, including special localized telephone numbers and
instructions and e-mail addresses for use in various languages.

Customers may only install and expect support for the feature sets they have
purchased. By installing, downloading, accessing or otherwise using such
software upgrades, customers agree to be bound by the terms of Cisco's software
license terms found at http://www.cisco.com/public/sw-license-agreement.html,
or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public
/sw-center/sw-usingswc.shtml.

Workarounds
===========

The effectiveness of any workaround is dependent on specific customer
situations such as product mix, network topology, traffic behavior, and
organizational mission. Due to the variety of affected products and releases,
customers should consult with their service provider or support organization to
ensure any applied workaround is the most appropriate for use in the intended
network before it is deployed.

In networks where IPv6 is not needed, disabling IPv6 processing on an IOS
device will eliminate exposure to this vulnerability. On a router which
supports IPv6, this must be done by issuing the command "no ipv6 enable" and
"no ipv6 address" on each interface.

Exploitation and Public Announcements
=====================================

This vulnerability was disclosed on July 27, 2005 at the Black Hat security
conference.

Status of This Notice: INTERIM
==============================

THIS ADVISORY IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF
GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF
THE INFORMATION ON THE ADVISORY OR MATERIALS LINKED FROM THE ADVISORY IS AT
YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS NOTICE AT ANY
TIME.

A stand-alone copy or paraphrase of the text of this security advisory that
omits the distribution URL in the following section is an uncontrolled copy,
and may lack important information or contain factual errors.

Distribution
============

This advisory will be posted on Cisco's worldwide website at http://
www.cisco.com/warp/public/707/cisco-sa-20050729-ipv6.shtml.

In addition to worldwide web posting, a text version of this notice is
clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail
and Usenet news recipients.

  * cust-security-announce@xxxxxxxxx
  * first-teams@xxxxxxxxx (includes CERT/CC)
  * bugtraq@xxxxxxxxxxxxxxxxx
  * vulnwatch@xxxxxxxxxxxxx
  * cisco@xxxxxxxxxxxxxxxxx
  * cisco-nsp@xxxxxxxxxxxxxxx
  * full-disclosure@xxxxxxxxxxxxxxxxx
  * comp.dcom.sys.cisco@xxxxxxxxxxxxxxxxxx

Future updates of this advisory, if any, will be placed on Cisco's worldwide
website, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
above URL for any updates.

Revision History
================

+---------------------------------------------+
| Revision  | 2005-July-29 | Initial public   |
| 1.0       |              | release.         |
+---------------------------------------------+

Cisco Security Procedures

Complete information on reporting security vulnerabilities in Cisco products,
obtaining assistance with security incidents, and registering to receive
security information from Cisco, is available on Cisco's worldwide website at
http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html
. This includes instructions for press inquiries regarding Cisco security
notices. All Cisco security advisories are available at http://www.cisco.com/go
/psirt.

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