Arbitrary DOM attributes in element.attributes and leaf.attributes in Platejs

Summary

Plate is a javascript toolkit that makes it easier for you to develop with Slate, a popular framework for building text editors. One longstanding feature of Plate is the ability to add custom DOM attributes to any element or leaf using the `attributes` property. These attributes are passed to the node component using the `nodeProps` prop. It has come to our attention that this feature can be used for malicious purposes, including cross-site scripting (XSS) and information exposure (specifically, users' IP addresses and whether or not they have opened a malicious document). Note that the risk of information exposure via attributes is only relevant to applications in which web requests to arbitrary URLs are not ordinarily allowed. Plate editors that allow users to embed images from arbitrary URLs, for example, already carry the risk of leaking users' IP addresses to third parties. All Plate editors using an affected version of @udecode/plate-core are vulnerable to these information exposure attacks via the style attribute and other attributes that can cause web requests to be sent. In addition, whether or not a Plate editor is vulnerable to cross-site scripting attacks using attributes depends on a number of factors. The most likely DOM attributes to be vulnerable are href and src on links and iframes respectively. Any component that spreads {...nodeProps} onto an <a> or <iframe> element and does not later override href or src will be vulnerable to XSS. In patched versions of Plate, we have disabled element.attributes and leaf.attributes for most attribute names by default, with some exceptions including target, alt, width, height, colspan and rowspan on the link, image, video, table cell and table header cell plugins. If this is a breaking change for you, you can selectively re-enable attributes for certain plugins as follows. Please carefully research and assess the security implications of any attribute you allow, as even seemingly innocuous attributes such as style can be used maliciously. If you are unable to upgrade to any of the patched versions, you should use a tool like patch-package or yarn patch to remove the logic from @udecode/plate-core that adds attributes to nodeProps.