Bug 301280 – [SVG2] Allow <foreignObject> and HTML elements to be cloned to the shadow tree of the <use> element

• Status: NEW
• Component: SVG

[Said Abou-Hallawa]

SVG2 made it possible for the <use> element to clone many elements that were previously disallowed, such as <foreignObject> [1]. The new WPT test will verify this new change in the SVG2 specs [2].

[1]: https://svgwg.org/svg2-draft/struct.html#UseElement:~:text=Previous%20versions%20of%20SVG,subtree%20to%20be%20cloned
[2]: https://github.com/web-platform-tests/wpt/pull/55576

[Robert Longson]

Be careful of https://bugzilla.mozilla.org/show_bug.cgi?id=1754522 when implementing this.

[Radar WebKit Bug Importer]

<rdar://problem/163647399>

[Karl Dubost]

Created attachment 478719 [details]
rendering in safari, firefox, chrome

https://github.com/web-platform-tests/wpt/pull/55576
https://wpt.fyi/results/svg/struct/reftests/use-foreignObject.html
https://wpt.live/svg/struct/reftests/use-foreignObject.html

PASS Firefox
FAIL Chrome, Safari

Spec prose in SVG2

> Previous versions of SVG restricted the contents of the shadow tree to SVG graphics elements. This specification allows any valid SVG document subtree to be cloned. Cloning non-graphical content, however, will not usually have any visible effect.

https://w3c.github.io/svgwg/svg2-draft/struct.html#UseElement:~:text=Previous%20versions%20of%20SVG,subtree%20to%20be%20cloned.

[Karl Dubost]

As Robert Longson mentions, we need to make sure of solving "XSS in SVG's foreignObject with iframe, loaded through a same-origin SVG file from a <use> element"