[WEB-4091] Certain Words in Password Break Minecraft Auth Server, Regardless of Username

I haven't played Minecraft in a while, but today I went to log in and I got this issue (after digging a bit):

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML><HEAD><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<TITLE>ERROR: The request could not be satisfied</TITLE>
</HEAD><BODY>
<H1>403 ERROR</H1>
<H2>The request could not be satisfied.</H2>
<HR noshade size="1px">
Request blocked. We can't connect to the server for this app or website at this time. There might be too much traffic or a configuration error. Try again later, or contact the app or website owner.
<BR clear="all">
If you provide content to customers through CloudFront, you can find steps to troubleshoot and help prevent this error by reviewing the CloudFront documentation.
<BR clear="all">
<HR noshade size="1px">
<PRE>
Generated by cloudfront (CloudFront) Request ID: ZngRp66EaEZRahoHs-Rj2QqSc6gdwTZ5e2UjqUPfxH6VlxtjNxBCnQ==
</PRE>
<ADDRESS>
</ADDRESS>
</BODY></HTML>

I tracked the issue down to my password: if this password is used with any email address / username, it causes this error (I have since changed my password to play Minecraft):

scp-R/root@127.0.0.1:/

This could be something with a misconfigured filter or something, I'm not a security expert. The least I could ask for is that I get a proper error message instead of the website failing silently. I had to manually send a request with cURL to get this message back (and I also found it in Chrome and Firefox dev tools).