Yesterday, I applied the patch from apache2-prefork-2.4.6-6.47.1.x86_64 to apache2-prefork-2.4.6-6.50.1.x86_64 and our rather complicated proxy configuration began serving blank pages.  There were no errors logged.  We proxy most of our web pages from our server to a CMS hosted centrally by the University.

It works fine when apache2-prefork-2.4.6-6.47.1.x86_64 is installed, even when I leave the other 2.46.6.50 patches installed, but serves up blank pages  when the update is installed.  I suspect there is a bug in mod_proxy, mod_proxy_http or mod_rewrite, but I have been unable to isolate the problem to one of these modules.

Here is a greatly simplified version of our proxy rules that demonstrates the problem:

    ProxyPass / http://foo.bar.com/site/
    ProxyPassReverse / http://foo.bar.com/site/


    <Location "/">
            RequestHeader append X-Forwarded-Path " "
    </Location>

    <Proxy *>
       Order allow,deny
       Allow from all
    </Proxy>

This configuration works fine under apache2-prefork-2.4.6-6.47.1.x86_64, but serves a blank page under apache2-prefork-2.4.6-6.50.1.x86_64.  No changes are made, except to install the newer version of apache2-prefork and restart the web server.