Unifiltered text can be inserted via Link Image To field when side-loading media

[DrewAPicture]

It looks like the replace methods were left out for f.url.value in wp-admin/includes/media.php. Thus, unfiltered text including complete javascript strings can be passed through the 'Link Image To' field when side-loading media via the 'From URL' tab. The unfiltered text is dropped untouched into the media's link tag and has potential to wreak havoc.

Reproduce:

In posting page-> Add media > Goto 'From URL' tab > Input a url to a valid remote image > Input special characters into the 'Link Image To' field > Insert into post.

[DrewAPicture]

Tested on trunk and inserted, side-loaded media URLs are now filtered as expected.

[DrewAPicture]

Remade patch root-relative at 18759

[azaozz]

In [19275]:

Filter the link href when inserting external image in the editor, props DrewAPicture, fixes #18445