Cisco Nexus 9000 ACI Switches EPG Contract Bypass Vulnerability
Cisco disclosed CVE-2026-20038, a medium-severity flaw in the endpoint group contract functionality of Nexus 9000 Series Fabric Switches in ACI Mode. An unauthenticated remote attacker can bypass configured EPG contracts by sending IPv4 or IPv6 packets using UDP source and destination ports assigned to DHCP traffic. Cisco released software updates; no workarounds exist.
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