CVE-2026-20173 Cisco NX-OS Software Denial of Service Vulnerability
An unauthenticated remote attacker can cause a denial of service by sending high-rate UDP or TCP traffic to data plane interfaces, exhausting system resources.
- 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-2026-20173?
CVE-2026-20173 is a medium-severity denial of service vulnerability in Cisco NX-OS Software, 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 Cisco NX-OS Software could allow an unauthenticated, remote attacker to exhaust system resources, causing a denial of service (DoS) condition. This vulnerability exists because rate limiting was improperly applied to some protocols. An attacker could exploit this vulnerability by sending a high rate of UDP or TCP connections to a data plane interface on an affected device. A successful exploit could allow the attacker to cause instability to various routing and control plane protocols through some packet loss and temporary disruptions, causing a DoS condition. This DoS condition will clear without manual intervention soon after the high rate of traffic is stopped.
Weakness: CWE-770
Which versions are affected by CVE-2026-20173?
How do I fix CVE-2026-20173?
No fix has been published for CVE-2026-20173 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-20173 being exploited?
There is no known exploitation of CVE-2026-20173 in the wild and no public exploit code.
Sources
Also known as GHSA-8g9j-7mq6-rw6g.