CVE-2021-22976 Denial of service in BIG-IP Advanced WAF & BIG-IP ASM

High 7.5 Published 12 Feb 2021 Updated 3 Aug 2024

Attackers can cause excessive CPU usage and denial of service by sending WebSocket requests with unusually large JSON payloads to BIG-IP ASM.

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-2021-22976?

CVE-2021-22976 is a high-severity denial of service vulnerability in F5 Big-Ip Advanced Web Application Firewall, published on 12 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

On BIG-IP Advanced WAF and ASM version 16.0.x before 16.0.1.1, 15.1.x before 15.1.2, 14.1.x before 14.1.3.1, 13.1.x before 13.1.3.6, and all 12.1.x versions, when the BIG-IP ASM system processes WebSocket requests with JSON payloads, an unusually large number of parameters can cause excessive CPU usage in the BIG-IP ASM bd process. Note: Software versions which have reached End of Software Development (EoSD) are not evaluated.

Which versions are affected by CVE-2021-22976?

It affects 2 products.

Products include F5 Big-Ip Advanced Web Application Firewall, F5 Big-Ip Application Security Manager.

How do I fix CVE-2021-22976?

No fix has been published for CVE-2021-22976 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-2021-22976 being exploited?

There is no known exploitation of CVE-2021-22976 in the wild and no public exploit code.

All F5 Big-Ip Advanced Web Application Firewall vulnerabilities

Sources

Also known as GHSA-5m63-vxpq-9j8m.