CVE-2021-43803 is a vulnerability that was first reported in September 2021. This vulnerability affects the Apache HTTP Server, which is an open-source web server software that is widely used across the internet. The vulnerability allows an attacker to launch a denial-of-service (DoS) attack on a targeted server by sending specially crafted requests. Successful exploitation of this vulnerability could result in the targeted server becoming unresponsive or crashing.
The vulnerability was caused by a flaw in the way the Apache HTTP Server handles certain requests from clients. Specifically, the issue was related to the "LimitRequestBody" directive, which is used to limit the size of request bodies that the server can handle. Attackers could exploit this flaw by sending large, invalid requests that would trigger the server to consume excessive resources and become unresponsive.
Fortunately, the vulnerability was quickly addressed by the Apache Software Foundation, which released a patch to fix the issue. System administrators are advised to update their Apache HTTP Server installations to the latest version as soon as possible to ensure that their systems are protected against this vulnerability. Additionally, it is recommended to implement network-level protections, such as firewalls and intrusion detection systems, to help prevent attacks targeting this vulnerability.