Apache 2.2.20 is was released Tuesday and the new content mostly comprises the bug fix. The vulnerability in Apache lies in the way that the server handles multiple overlapping ranges in Range headers. An attack tool that can exploit the vulnerability is circulating online and researchers say they have seen attacks utilizing the tool. Cisco released a security advisory warning customers that a number of its products are vulnerable to the Apache header problem. The list of vulnerable products includes: Cisco MDS 9000 NX-OS Software releases prior to 4.2x are not affected.
Source: https://threatpost.com/apache-fixes-range-header-dos-flaw-083111/75598/