http profile

It sounds like you are talking about using the F5 ASM module and the ASM module is disallowing certain metacharacters? If so I would start by reviewing this document SOL6787: Working with metacharacters in the BIG-IP ASM security policy

If you are just using LTM, this from the v11.4 release notes may help you:

ID 389325This release adds four BigDB variables to control the behavior of the HTTP filter when it encounters invalid HTTP traffic. These new options are disabled by default. Important: The last three of these should be used only in a transparent proxy configuration. No checking is done once the HTTP filter switches to pass-through mode, and arbitrary traffic could proceed down the now open tunnel. Tmm.HTTP.passthru.truncated_redirect - For invalid HTTP redirects with missing trailing carriage returns, forwards the redirects to the client instead of dropping them. Tmm.HTTP.passthru.invalid_header - For traffic with invalid HTTP headers, passes through the traffic instead of dropping it. Tmm.HTTP.passthru.unknown_method - Treats unknown HTTP extension methods as 'invalid.' You can combine this method with the previous flag to cause unknown HTTP extension methods to be passed through. Tmm.HTTP.passthru.pipeline - Upon receipt of pipelined data, the HTTP filter switches to pass-through mode. This is useful when HTTP non-compliant traffic breaks the request-response idiom, for example, by sending binary data after a GET, and expecting that the data is sent to the server before that server responds to the earlier GET request.