Secunia

A vulnerability has been reported in Cisco IOS and IOS XR, which can be exploited by malicious people to potentially disclose sensitive information or to cause a DoS (Denial of Service).

The vulnerability is caused due to an error when processing IPv6 packets with a Type 0 routing header. This can lead to disclosure of 16 bytes of packet buffer memory in the destination IPv6 address in a IPv6 packet header, and can also be exploited to crash an IOS device or the IPv6 subsystem on devices running Cisco IOS XR by sending a specially crafted IPv6 packet.

Successful exploitation requires that the device is configured to use IPv6.

The following products are reportedly not affected:
* Cisco PIX and ASA Appliances
* Cisco Firewall Services Module (FWSM)
* Cisco MDS

Solution
Apply updated versions. See vendor advisory for more details.
Further details available in Customer Area

Provided and/or discovered by
Reported by the vendor, who also credits Tom Cross, IBM ISS X-Force.

Changelog
Further details available in Customer Area

Original Advisory
http://www.cisco.com/warp/public/707/cisco-sa-20070808-IOS-IPv6-leak.shtml

Deep Links
Links available in Customer Area