This indicates an attack attempt to exploit a Security Policy Bypass Vulnerability in Apache Software Foundation httpd.
The vulnerability is due to an error in the vulnerable application when handling a maliciously crafted request. A remote attacker may be able to exploit this to upload a file that is not permitted within the context of the application, via a crafted request.
Apache Software Foundation httpd 2.4.x Prior to 2.4.30
Security Bypass: Remote attackers can bypass security features of vulnerable systems.
Apply the most recent upgrade or patch from the vendor: