Try/strip custom block css without unfiltered html#76167
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…bility - Added a function to remove block-level custom CSS when saving content for restricted users. - Introduced a warning message in the editor for blocks with custom CSS that will be stripped on save. - Updated styles to visually indicate blocks affected by this change. This ensures that users without the ability to use unfiltered HTML do not inadvertently save custom CSS that could lead to issues.
- Integrated BlockCustomCSSStripNotice component into the editor interface to provide users with warnings about custom CSS being stripped for those without unfiltered_html capability. - This enhances user awareness regarding the handling of custom CSS in the editor. This change supports the previous functionality of stripping custom CSS for restricted users by ensuring they receive appropriate notifications.
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Size Change: +385 B (+0.01%) Total Size: 6.87 MB
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ramonjd
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Mar 5, 2026
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| $blocks = parse_blocks( $content ); | ||
| $blocks = gutenberg_strip_custom_css_from_blocks( $blocks ); | ||
| return serialize_blocks( $blocks ); |
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is there a better / faster way to do this? I guess in the Core path it'll be working at the block level anyway:
https://github.com/wordpress/wordpress-develop/blob/trunk/src/wp-includes/blocks.php#L2078
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What
In this PR, for users without
unfiltered_htmlsave posts that contain block-level custom CSS, that CSS is now stripped (not passed through KSES), and the editor throws up a warning so they know it will be removed.Why
This avoids KSES corrupting
&and>in CSS (e.g. nesting/selectors) and makes the behavior explicit.How
pre_kses(priority 5), stripattrs.style.cssfrom all blocks for users withoutunfiltered_htmlso it is never run through KSES (lib/experimental/kses.php).Test steps
unfiltered_html). As Admin, create a post, add a block (e.g. Paragraph), open Advanced → Additional CSS, add e.g.color: blue; & p { color: red; }, save.&/>in saved content.