We could use some help tracking down a consistent error on our Craft installs according to Acunetix Security Audits.
URL Rewrite Vulnerability
It was identified that this application supports the legacy headers X-Original-URL and/or X-Rewrite-URL.
Support for these headers lets users override the path in the request URL via the X-Original-URL or X-Rewrite-URL HTTP request header and allows a user to access one URL but have web application return a different one which can bypass restrictions on higher level caches and web servers.
Many web frameworks such as Symfony 2.7.0 to 2.7.48, 2.8.0 to 2.8.43, 3.3.0 to 3.3.17, 3.4.0 to 3.4.13, 4.0.0 to 4.0.13 and 4.1.0 to 4.1.2 , zend-diactoros up to 1.8.4, zend-http up to 2.8.1, zend-feed up to 2.10.3 are affected by this security issue.
These sites are hosted on Forge / Linode servers.
Versions vary, but most are recent-ish Craft 2.X
A couple (though not all) use the Redirect Manager plugin