array_intersect_key() fatal error in wp_render_layout_support_flag() due to invalid string parentLayout in core/social-links block

[devksec]

When using the core/social-links block, WordPress core may crash with a fatal error:

PHP Fatal error: Uncaught TypeError: array_intersect_key(): Argument #1 ($array) must be of type array, string given in wp-includes/block-supports/layout.php

This occurs because parentLayout is being passed as a string ("flex") instead of an array, likely during automatic layout injection in block rendering. Since wp_render_layout_support_flag() assumes both $blockattrs?style?layout? and $blockparentLayout? are arrays, it causes array_intersect_key() to throw a fatal.

Steps to reproduce:

1. Use a block template or block theme with core/social-links

2. Enable full site editing or a block-based page layout

3. Attempt to render the template or page

4. Fatal error occurs on line 600+ in layout.php

Proposed fix:
Core layout support logic should include:

php
Copy
Edit
if ( is_array( $blockparentLayout? ) ) {

only process layout

}
Or handle invalid structures more gracefully (e.g. log + fallback).

Workaround:
We patched layout.php by validating both layout and parentLayout as arrays before calling array_intersect_key().

Impact:
Breaks front-end rendering for many sites using block-based layouts.

Likely triggered by changes in layout-aware blocks like core/social-links or reusable block wrappers.

[abcd95]

Hi @devksec, Thanks for the report.

After testing multiple ways and all possibilities, I was still unable to observe any fatal error. I followed the steps you mentioned.

Could you help with any screenshots or screencasts if possible?

[devksec]

Hello,

Thanks for the prompt reply.

Here’s more detailed evidence:

PHP Fatal error: Uncaught TypeError: array_intersect_key(): Argument #1 ($array) must be of type array, string given in /wp-includes/block-supports/layout.php on line 600
Stack trace:
#0 /wp-includes/block-supports/layout.php(600): array_intersect_key()
#1 /wp-includes/class-wp-hook.php(326): wp_render_layout_support_flag()
#2 /wp-includes/plugin.php(205): WP_Hook->apply_filters()
#3 /wp-includes/class-wp-block.php(638): apply_filters()
...

Debug output showing the invalid structure injected:

[DEBUG] Invalid parentLayout: flex
[DEBUG] Block with bad parentLayout: Array
(

[blockName] => core/social-links
[attrs] => Array

(

[layout] => Array

(

[type] => flex
[orientation] => horizontal
[justifyContent] => space-between
[flexWrap] => nowrap

)

...

)

[parentLayout] => flex

)

Notice parentLayout => flex is passed as a string, not an array.
When WordPress tries to array_intersect_key() this string, the fatal occurs.

What triggered this:
Using core/social-links inside a block theme layout

Site uses full-site editing templates

Running WordPress 6.5.2

No Spectra or third-party block plugin involved in this specific crash

Additional notes:

Manually validating that parentLayout is an array inside layout.php prevents the fatal and allows the page to render normally.

Issue occurs when layout-aware processing (wp_render_layout_support_flag) tries to apply to child blocks automatically.

Would you also like me to provide a copy of the sample template where this happens?

Happy to assist further!

Best regards,

[abcd95]

Hey @devksec, Thanks for the detailed report.

I've been trying to reproduce the issue you've described, but haven't been successful so far despite following several approaches.

• Created templates with various configurations of the core/social-links block using the site editor
• Placed social links inside Group blocks with flex layout
• Tested different nesting levels (Group > Columns > Group > Social Links)
• Configured the social links block with horizontal orientation and space-between justification
• Viewed the templates on the front-end to check for the fatal error

I wasn't able to trigger the array_intersect_key() error you mentioned. Is there something more to be done here?