HTTP_AUTHORIZATION is called REDIRECT_HTTP_AUTHORIZATION on some server configurations

[panic175]

The prefix is present on some configurations of PHP with FastCGI. So I guess OAuth1 should check for both.
See here: WP-API/api-console#1 (comment)

[joehoyle]

Hmm I'm not sure if this is any official header and therefore should be included, I'm leaning towards no, but let's open this for discussion.

[fatica]

I'd like to mention that we see this regularly.

Where REDIRECT_HTTP_AUTHORIZATION is present, but HTTP_AUTHORIZATION is not.

I understand this occurs when PHP is running in FastCGI mode and the HTTP_AUTHORIZATION is set via SetEnv or .htaccess directives such as

RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}

FWIW the same issue occurs in the Wordpress Basic Auth plugin.

We've handled this as described in this article:
https://www.metalocator.com/wp-json-basic-auth-with-fastcgi/