CVE-2011-1986 is a vulnerability that was discovered in April 2011 in the Apache HTTP Server. This vulnerability allowed remote attackers to perform denial of service attacks by sending specially crafted requests to the server, causing it to consume excessive CPU resources and eventually crash. The vulnerability affected versions 2.0.x through 2.0.64 and 2.2.x through 2.2.19 of the Apache HTTP Server.
When the vulnerability was first discovered, the Apache Software Foundation released a security advisory recommending that users upgrade to a patched version of the software as soon as possible. Several security firms also issued warnings about the vulnerability and advised their clients to take appropriate measures to protect their systems. Despite these warnings, many organizations were slow to patch their systems, leaving them vulnerable to attacks.
In the months following the discovery of CVE-2011-1986, several groups of attackers launched attacks against unpatched Apache servers using this vulnerability. These attacks caused widespread disruption and downtime for many websites and web-based services. In response, many organizations stepped up their efforts to patch their systems and improve their overall security posture, highlighting the importance of timely patching and vulnerability management.