GHSA-gpqq-952q-5327

### Impact
Accepting the value of the `of` option of the [`.position()`](https://api.jqueryui.com/position/) util from untrusted sources may execute untrusted code. For example, invoking the following code:
```js
$( "#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](https://github.com/jquery/jquery-ui/issues). If you don't find an answer, open a new issue.