Extended HTML Filter security updates, in plain English

Extended HTML Filter

1,714 sites report using it · on drupal.org · 1 security update explained here

This module allows editors to add custom visual styles to text when writing content.

Below is every security update for Extended HTML Filter that this site has covered, newest first. Each one says who could exploit it, whether it applies to your site, how urgent it is, and what to tell your developer. If your site uses this module and you are not sure which version, that is the first question to ask whoever looks after it.

Extended HTML Filter

Moderately critical · 1,714 sites report using it · SA-CONTRIB-2026-309 · on drupal.org · Week of 4 November 2026

The module does not properly clean up certain text attributes. An ordinary account on the site could use this to run unwanted scripts. This might allow them to view private details or modify existing content.

Who could do thisOnly someone with a login on your site.
Does it apply to youSites are affected if an attacker is able to insert text with specific attributes.
Has it been used in attacksNo sign of it.
How urgentDrupal rates this moderately critical. Include it in your next routine update, within the month.

Tell your developerUpdate Extended HTML Filter to 1.0.4.

For developers: what the fix changed

The fix adds checks to skip attributes starting with 'data-hx' or 'hx' in the ExtendedHTMLFilterXss class to prevent XSS via HTMX attributes.

Also in this release The release also updates strpos checks to str_starts_with for better readability and performance.

1.0.3 to 1.0.4 1 commit, 1 file.

src/Utility/ExtendedHTMLFilterXss.php +4 −2 fix

Full diff, 1.0.3 to 1.0.4

The comparison is against the release immediately before the fix. If your site is on an older release, more will have changed.

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Extended HTML Filter

Extended HTML Filter

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