CVE-2026-20038 Cisco Nexus 9000 Series Fabric Switches in ACI Mode Policy-Based Redirect Endpoint Group Contract Bypass Vulnerability
Unauthenticated remote attackers can bypass EPG contracts on Cisco Nexus 9000 switches in ACI mode by sending specific UDP packets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20038?
CVE-2026-20038 is a medium-severity vulnerability in Cisco NX-OS System Software in ACI Mode, published on 7 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the endpoint group (EPG) contract functionality of Cisco Nexus 9000 Series Fabric Switches in ACI Mode could allow an unauthenticated, remote attacker to bypass configured EPG contracts. This vulnerability is due to an improper control with EPG contracts. An attacker could exploit this vulnerability by sending IPv4 or IPv6 packets using UDP source and destination ports that are assigned to DHCP traffic through an affected device. A successful exploit could allow the attacker to bypass EPG contracts on the affected device.
Weakness: CWE-284
Which versions are affected by CVE-2026-20038?
How do I fix CVE-2026-20038?
No fix has been published for CVE-2026-20038 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-20038 being exploited?
There is no known exploitation of CVE-2026-20038 in the wild and no public exploit code.
Sources
Also known as GHSA-8r87-mj76-xw8h.