CVE-2015-4321: The Unicast Reverse Path Forwarding (uRPF) implementation in Cisco Adaptive Security Appliance (ASA) Softwa...

Security readout for executives and security teams

This flaw weakens a Cisco ASA firewall anti-spoofing control. In specific ASA releases, uRPF can wrongly allow spoofed packets when an internal interface address also appears in the routing table. That does not mean firewall compromise, but it can reduce trust in traffic-source validation at the network edge. Exposure is most likely where affected Cisco ASA versions are deployed with uRPF relied on for anti-spoofing. The bundle does not establish whether vulnerable behavior requires non-default routing or interface configurations beyond the described overlap condition. Handle as a targeted network-control bypass, not a broad system takeover. Prioritize internet-edge and high-trust segmentation firewalls first, especially where anti-spoofing is a compliance or security dependency. Mitigation focus: Identify Cisco ASA devices running the named affected versions.; Review Cisco advisory guidance for fixed releases or vendor-supported workarounds.; Prioritize remediation where uRPF enforces perimeter anti-spoofing controls..

Prepared

Jun 13, 2026, 22:03 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.