I'm learning SSRF. I learnt that typing "&x=" kinda turn off the rest of an URL (like https://some.website.com/user?id=9&x=.website.com/api/item?id=9)

Everything that comes after the "&x=" part gets ignored. Why is that? Or, if it's not really ignored, then what happens?

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  • "&" is just to include additional query parameters. Once the "?" is hit, the rest of the URL will be processed as GET key/value pairs.
    – pcalkins
    Aug 4 at 18:11

1 Answer 1


It's not related to encoding in this case.

According to the RFC 3986 Regular Expression of ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))? does not allow parsing of another ? after a &, which denotes a second and so forth parameter.

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