Cross-Site-Scripting attack on `<RichTextField>`

Impact

All React applications built with react-admin and using the <RichTextField> are affected.

<RichTextField> outputs the field value using dangerouslySetInnerHTML without client-side sanitization. If the data isn’t sanitized server-side, this opens a possible Cross-Site-Scripting (XSS) attack.

Proof of concept:

import { RichTextField } from 'react-admin';

const record = {
    id: 1,
    body: `
<p>
<strong>War and Peace</strong> is a novel by the Russian author
<a href="https://en.wikipedia.org/wiki/Leo_Tolstoy">Leo Tolstoy</a>,
published serially, then in its entirety in 1869.
</p>
<p>
It is regarded as one of Tolstoy's finest literary achievements and remains a classic of world literature.
</p>
<img src />
`,
};

const VulnerableRichTextField = () =&gt; (
    &lt;&gt;
        &lt;RichTextField record={record} source="body" /&gt;
        <hr />
        <h4>Stolen data:</h4>
        &lt;input id="stolendata" defaultValue="none" /&gt;
    &lt;/&gt;
);

Patches

Versions 3.19.12 and 4.7.6 now use DOMPurify to escape the HTML before outputting it with React and dangerouslySetInnerHTML

Workarounds

You don’t need to upgrade if you already sanitize HTML data server-side.

Otherwise, you’ll have to replace the <RichTextField> by a custom field doing sanitization by hand:

// react-admin v4
import * as React from 'react';
import { memo } from 'react';
import PropTypes from 'prop-types';
import get from 'lodash/get';
import Typography from '@material-ui/core/Typography';
import { useRecordContext, sanitizeFieldRestProps, fieldPropTypes } from 'react-admin';
import purify from 'dompurify';

export const removeTags = (input) =>
    input ? input.replace(/<[^>]+>/gm, '') : '';

const RichTextField = memo(
    props => {
        const { className, emptyText, source, stripTags, ...rest } = props;
        const record = useRecordContext(props);
        const value = get(record, source);

        return (
            <Typography
                className={className}
                variant="body2"
                component="span"
                {...sanitizeFieldRestProps(rest)}
            >
                {value == null && emptyText ? (
                    emptyText
                ) : stripTags ? (
                    removeTags(value)
                ) : (
                    <span />
                )}
            &lt;/Typography&gt;
        );
    }
);

RichTextField.defaultProps = {
    addLabel: true,
    stripTags: false,
};

RichTextField.propTypes = {
    // @ts-ignore
    ...Typography.propTypes,
    ...fieldPropTypes,
    stripTags: PropTypes.bool,
};

RichTextField.displayName = 'RichTextField';

export default RichTextField;

References

https://github.com/marmelab/react-admin/pull/8644, https://github.com/marmelab/react-admin/pull/8645