CVE-2020-27718 Denial of service in BIG-IP ASM & Advanced WAF

High 7.5 Published 24 Dec 2020 Updated 4 Aug 2024

Attackers can cause excessive CPU usage and denial of service in BIG-IP ASM or Advanced WAF by sending JSON requests with an unusually large number of parameters.

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-2020-27718?

CVE-2020-27718 is a high-severity denial of service vulnerability in F5 Big-Ip Advanced Web Application Firewall, published on 24 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

When a BIG-IP ASM or Advanced WAF system running version 16.0.0-16.0.0.1, 15.1.0-15.1.0.5, 14.1.0-14.1.3, 13.1.0-13.1.3.4, 12.1.0-12.1.5.2, or 11.6.1-11.6.5.2 processes requests with JSON payload, an unusually large number of parameters can cause excessive CPU usage in the BIG-IP ASM bd process.

Which versions are affected by CVE-2020-27718?

It affects 2 products.

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

How do I fix CVE-2020-27718?

No fix has been published for CVE-2020-27718 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-2020-27718 being exploited?

There is no known exploitation of CVE-2020-27718 in the wild and no public exploit code.

All F5 Big-Ip Advanced Web Application Firewall vulnerabilities

Sources

Also known as GHSA-gmqq-hrf4-4gvf.