K000138898 : BIG-IP Advanced WAF/ASM, BIG-IP Next WAF, and NGINX App Protect WAF attack signature check failure

Security Advisory Description

BIG-IP Advanced WAF/ASM, BIG-IP Next WAF, or NGINX App Protect WAF may fail to match an attack signature.

This issue occurs when all of the following conditions are met:

• The affected security policy has a large number of attack signatures enabled (for example, all or most F5 provided signatures).
• A number of custom attack signatures is created and enabled on the affected security policy.

Impact

An attacker may be able to bypass the affected attack signature. As a result, the backend servers protected by the BIG-IP Advanced WAF/ASM, BIG-IP Next WAF, or NGINX App Protect WAF may be exposed to a vulnerability due to the bypassed attack signature.

Symptoms

As a result of this issue, you may encounter the following symptom:

• The backend servers protected by the BIG-IP Advanced WAF/ASM, BIG-IP Next WAF, or NGINX App Protect WAF may be exposed to a vulnerability due to the bypassed attack signature.