Cisco Security Advisory – Cisco Catalyst 6500 series systems that are running certain versions of Cisco Internetwork Operating System (IOS) are vulnerable to an attack from a Multi Protocol Label Switching (MPLS) packet. Only the systems that are running in Hybrid Mode (Catalyst OS (CatOS) software on the Supervisor Engine and IOS Software on the Multilayer Switch Feature Card (MSFC)) or running with Cisco IOS Software Modularity are affected.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/54811/cisco-sa-20070228-mpls.txt
Source: https://packetstormsecurity.com/files/54811/Cisco-Security-Advisory-20070228-mpls.html