A vulnerability in the logic that handles access control to one of the hardware components in Cisco's proprietary Secure Boot implementation could allow an authenticated, local attacker to write a modified firmware image to the component. This vulnerability affects multiple Cisco products that support hardware-based Secure Boot functionality. The vulnerability is due to an improper check on the area of code that manages on-premise updates to a Field Programmable Gate Array (FPGA) part of the Secure Boot hardware implementation. An attacker with elevated privileges and access to the underlying operating system that is running on the affected device could exploit this vulnerability by writing a modified firmware image to the FPGA. A successful exploit could either cause the device to become unusable (and require a hardware replacement) or allow tampering with the Secure Boot verification process, which under some circumstances may allow the attacker to install and boot a malicious softw…

The Neighbor Discovery (ND) protocol implementation in the IPv6 stack in Cisco IOS XE 2.1 through 3.17S, IOS XR 2.0.0 through 5.3.2, and NX-OS allows remote attackers to cause a denial of service (packet-processing outage) via crafted ND messages, aka Bug ID CSCuz66542, as exploited in the wild in May 2016.

Multiple buffer overflows in the Cisco Discovery Protocol (CDP) implementation in Cisco NX-OS on Nexus 7000 devices 4.x and 5.x before 5.2(4) and 6.x before 6.1(1), Nexus 5000 and 5500 devices 4.x and 5.x before 5.1(3)N1(1), Nexus 4000 devices before 4.1(2)E1(1h), Nexus 3000 devices 5.x before 5.0(3)U3(1), Nexus 1000V devices 4.x before 4.2(1)SV1(5.1), MDS 9000 devices 4.x and 5.x before 5.2(4), Unified Computing System (UCS) 6100 and 6200 devices before 2.0(2m), and Connected Grid Router (CGR) 1000 devices before CG4(1) allow remote attackers to execute arbitrary code via malformed CDP packets, aka Bug IDs CSCtu10630, CSCtu10551, CSCtu10550, CSCtw56581, CSCtu10548, CSCtu10544, and CSCuf61275.

The ACL implementation in Cisco NX-OS 5.0(2) and 5.0(3) before 5.0(3)N2(1) on Nexus 5000 series switches, and NX-OS before 5.0(3)U1(2a) on Nexus 3000 series switches, does not properly handle comments in conjunction with deny statements, which allows remote attackers to bypass intended access restrictions in opportunistic circumstances by sending packets, aka Bug IDs CSCto09813 and CSCtr61490.