The bug in question is a Denial-of-Service vulnerability that allows the attacker to execute the attack remotely and to take over a great amount of memory and CPU usage with only a modest number of request directed at the Web Server.
And even though the vulnerability has been spotted more than four years ago by Google security engineer Michal Zalewski, it has never been patched.
The attack can be deployed against all versions in the 1.3 and 2.0 lines, but as the Foundation no longer supports the 1.3 line, a patch will be issued only for Apache 2.0 and 2.2, and it should be out by Friday evening.
While waiting for it, administrators have been provided with a number of mitigation steps that should prevent attacks against their server.
By subscribing to our early morning news update, you will receive a daily digest of the latest security news published on Help Net Security.
With over 500 issues so far, reading our newsletter every Monday morning will keep you up-to-date with security risks out there.