CVE-2021-23000 Denial of service in BIG-IP

High 7.5 Published 31 Mar 2021 Updated 3 Aug 2024

Attackers can cause TMM restarts via malicious requests if specific HTTP enforcement settings are enabled, impacting availability.

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-2021-23000?

CVE-2021-23000 is a high-severity denial of service vulnerability in F5 Big-Ip Access Policy Manager, published on 31 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

On BIG-IP versions 13.1.3.4-13.1.3.6 and 12.1.5.2, if the tmm.http.rfc.enforcement BigDB key is enabled in a BIG-IP system, or the Bad host header value is checked in the AFM HTTP security profile associated with a virtual server, in rare instances, a specific sequence of malicious requests may cause TMM to restart. Note: Software versions which have reached End of Software Development (EoSD) are not evaluated.

Which versions are affected by CVE-2021-23000?

It affects 14 products.

Products include F5 Big-Ip Access Policy Manager, F5 Big-Ip Advanced Firewall Manager, F5 Big-Ip Advanced Web Application Firewall, F5 Big-Ip Analytics, F5 Big-Ip Application Acceleration Manager, F5 Big-Ip Application Security Manager and 8 more.

How do I fix CVE-2021-23000?

No fix has been published for CVE-2021-23000 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-2021-23000 being exploited?

There is no known exploitation of CVE-2021-23000 in the wild and no public exploit code.

All F5 Big-Ip Access Policy Manager vulnerabilities

Sources

Also known as GHSA-6vhg-w9jf-mcqf.