---
title: "12.4.x Changes"
manual: "TYPO3 Core Changelog"
version: "main"
permalink: "https://docs.typo3.org/permalink/changelog:changelog-12-4-x"
source: "Changelog/12.4.x/Index.rst"
typo3-version: "12.4.x"
typo3-major: 12
rendered: "2026-09-17T21:17:42+00:00"
noindex: true
---

# 12.4.x Changes {#12-4-x-changes}

**Table of contents**

-   [Breaking Changes](https://docs.typo3.org/permalink/changelog:breaking-changes)
-   [Features](https://docs.typo3.org/permalink/changelog:features)
-   [Deprecation](https://docs.typo3.org/permalink/changelog:deprecation)
-   [Important](https://docs.typo3.org/permalink/changelog:important)

## Breaking Changes {#breaking-changes}

None since TYPO3 v12.4.0 LTS release.

> [!WARNING]
> **Attention**
>
> Breaking changes are not planned after the TYPO3 v12.4.0 LTS release.

## Features {#features}

-   [Feature: #106743 - Introduce Sudo-Mode Events](https://docs.typo3.org/permalink/changelog:feature-106743-introduce-sudo-mode-events)

> [!WARNING]
> **Attention**
>
> New features are not planned after the TYPO3 v12.4.0 LTS release.

## Deprecation {#deprecation}

-   [Deprecation: #102099 - Deprecate CKEditor 5 bundle module](https://docs.typo3.org/permalink/changelog:deprecation-102099-deprecate-ckeditor-5-bundle-module)

## Important {#important}

-   [Important: #96218 - Use proper surrounding "html" tags for Fluid SystemEmail](https://docs.typo3.org/permalink/changelog:important-96218-use-proper-surrounding-html-tags-for-fluid-systememail)
-   [Important: #99781 - Exporting and downloading records in the list module](https://docs.typo3.org/permalink/changelog:important-99781-exporting-and-downloading-records-in-the-list-module)
-   [Important: #100847 - Added font plugin to CKEditor 5](https://docs.typo3.org/permalink/changelog:important-100847-added-font-plugin-to-ckeditor-5)
-   [Important: #100889 - Allow insecure site resolution by query parameters](https://docs.typo3.org/permalink/changelog:important-100889-allow-insecure-site-resolution-by-query-parameters)
-   [Important: #100925 - Use dedicated cache for database schema information](https://docs.typo3.org/permalink/changelog:important-100925-use-dedicated-cache-for-database-schema-information)
-   [Important: #101128 - CKEditor's highlight plugin introduces mark HTML tag](https://docs.typo3.org/permalink/changelog:important-101128-ckeditor-s-highlight-plugin-introduces-mark-html-tag)
-   [Important: #101567 - Use Symfony attribute to autoconfigure cli commands](https://docs.typo3.org/permalink/changelog:important-101567-use-symfony-attribute-to-autoconfigure-cli-commands)
-   [Important: #101580 - Introduce Content-Security-Policy-Report-Only handling](https://docs.typo3.org/permalink/changelog:important-101580-introduce-content-security-policy-report-only-handling)
-   [Important: #101776 - Email validation in GeneralUtility::validEmail() now rejects spaces before "@"](https://docs.typo3.org/permalink/changelog:important-101776-email-validation-in-generalutility-validemail-now-rejects-spaces-before)
-   [Important: #102314 - Add title argument to IconViewhelper](https://docs.typo3.org/permalink/changelog:important-102314-add-title-argument-to-iconviewhelper)
-   [Important: #102507 - Default CKEditor 5 allowed classes and data attributes configurated reverted](https://docs.typo3.org/permalink/changelog:important-102507-default-ckeditor-5-allowed-classes-and-data-attributes-configurated-reverted)
-   [Important: #102904 - Use TCA group field as foreign selector](https://docs.typo3.org/permalink/changelog:important-102904-use-tca-group-field-as-foreign-selector)
-   [Important: #103392 - Form framework select markup changed](https://docs.typo3.org/permalink/changelog:important-103392-form-framework-select-markup-changed)
-   [Important: #103496 - ISO format used for date rendering](https://docs.typo3.org/permalink/changelog:important-103496-iso-format-used-for-date-rendering)
-   [Important: #104549 - Introduce site-specific Content-Security-Policy-Disposition](https://docs.typo3.org/permalink/changelog:important-104549-introduce-site-specific-content-security-policy-disposition)
-   [Important: #104693 - Setting allowLanguageSynchronization via columnsOverrides](https://docs.typo3.org/permalink/changelog:important-104693-setting-allowlanguagesynchronization-via-columnsoverrides)
-   [Important: #104827 - Allow to use Regular Expressions in CKEditor YAML](https://docs.typo3.org/permalink/changelog:important-104827-allow-to-use-regular-expressions-in-ckeditor-yaml)
-   [Important: #104839 - RTE processing YAML configuration now respects removeTags](https://docs.typo3.org/permalink/changelog:important-104839-rte-processing-yaml-configuration-now-respects-removetags)
-   [Important: #105856 - Allow site-specific Content-Security-Policy endpoints](https://docs.typo3.org/permalink/changelog:important-105856-allow-site-specific-content-security-policy-endpoints)
-   [Important: #106229 - Allow filtering request hosts in webhook messages](https://docs.typo3.org/permalink/changelog:important-106229-allow-filtering-request-hosts-in-webhook-messages)
-   [Important: #106240 - Enforce File Extension and MIME-Type Consistency in File Abstraction Layer](https://docs.typo3.org/permalink/changelog:important-106240-enforce-file-extension-and-mime-type-consistency-in-file-abstraction-layer)
-   [Important: #106715 - Apply CSP sandbox mode to fileadmin's .htaccess configuration](https://docs.typo3.org/permalink/changelog:important-106715-apply-csp-sandbox-mode-to-fileadmin-s-htaccess-configuration)
-   [Important: #106735 - File MIME Type compatiblity mapping](https://docs.typo3.org/permalink/changelog:important-106735-file-mime-type-compatiblity-mapping)
-   [Important: #106983 - Hardened access to module-related AJAX routes](https://docs.typo3.org/permalink/changelog:important-106983-hardened-access-to-module-related-ajax-routes)
-   [Important: #109176 - CKEditor hardened iframes by enforcing sandbox behavior](https://docs.typo3.org/permalink/changelog:important-109176-ckeditor-hardened-iframes-by-enforcing-sandbox-behavior)