The flaw, discovered by bug-hunter Auriemma Luigi, affects default installations of the Apache Web server in non-Unix platforms like Windows, OS2 and Netware. The flaw does not appear to affect Unix and other variant platforms, Cox said, though he noted that Cygwin users are likely to be affected. Luigi notified the Apache Software Foundation of the vulnerability on Wednesday.
Additionally, Cox said a one-line workaround in the httpd.conf file will close the vulnerability. He said that prior to the first 'Alias' or 'Redirect' directive, simply add the following directive to the global server configuration:
- RedirectMatch 400 "\\\.\."
Cox noted that fixes for the vulnerability are included in Apache version 2.0.40, in addition to fixes for a number of less serious security flaws.