XSS in the `of` option of the `.position()` util in jquery-ui

Impact

Accepting the value of the of option of the .position() util from untrusted sources may execute untrusted code. For example, invoking the following code:

$( "#element" ).position( {
	my: "left top",
	at: "right bottom",
	of: "<img onerror='doEvilThing()' src='/404' />",
	collision: "none"
} );

will call the doEvilThing() function.

Patches

The issue is fixed in jQuery UI 1.13.0. Any string value passed to the of option is now treated as a CSS selector.

Workarounds

A workaround is to not accept the value of the of option from untrusted sources.

For more information

If you have any questions or comments about this advisory, search for a relevant issue in the jQuery UI repo. If you don't find an answer, open a new issue.