CVE-2021-1523 Cisco Nexus 9000 Series Fabric Switches ACI Mode Queue Wedge Denial of Service Vulnerability
Unauthenticated remote attackers can cause a queue wedge on Cisco Nexus switches, dropping control plane traffic and requiring a power cycle to recover.
- 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-2021-1523?
CVE-2021-1523 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 25 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) Mode could allow an unauthenticated, remote attacker to cause a queue wedge on a leaf switch, which could result in critical control plane traffic to the device being dropped. This could result in one or more leaf switches being removed from the fabric. This vulnerability is due to mishandling of ingress TCP traffic to a specific port. An attacker could exploit this vulnerability by sending a stream of TCP packets to a specific port on a Switched Virtual Interface (SVI) configured on the device. A successful exploit could allow the attacker to cause a specific packet queue to queue network buffers but never process them, leading to an eventual queue wedge. This could cause control plane traffic to be dropped, resulting in a denial of service (DoS) condition where the leaf switches are unavailable. Note: This vulnerability requires a manual intervention to power-cycle the device to recover.
Weakness: CWE-772
Which versions are affected by CVE-2021-1523?
It affects 1 product.
Products include Cisco Nx-Os.
How do I fix CVE-2021-1523?
No fix has been published for CVE-2021-1523 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-2021-1523 being exploited?
There is no known exploitation of CVE-2021-1523 in the wild and no public exploit code.
Other vulnerabilities in Cisco Nx-Os
Sources
Also known as GHSA-f58x-5qwh-88r6.