In an updated and unadorned WordPress installation, with only the Classic Editor plugin enabled, and the 2017 theme, I get a weird error.

When I try to save a draft of a post containing this

<code>curl "http://localhost:64410/api/yoyo?value1=val&value2=val2"<code>

I always get a 403 Forbidden error on a splash page from WordPress. If I change it to

<code>curl -X GET "http://localhost:64410/api/yoyo?value1=val&value2=val2"<code>

or

<code>curl "localhost:64410/api/yoyo?value1=val&value2=val2"<code>

I don't get the 403 and the post goes through. Whisky Tango Foxtrot? I'm pretty sure I don't have anything misconfigured in my installation.

This looks like it might be some built-in cross-site-scripting-prevention trap or something. But it's an awfully crude error message.

Do you know how I can get my desired content into my post?

(I'm writing a tech post about web service development.)