diff --git a/typo3/sysext/core/Classes/Html/HtmlParser.php b/typo3/sysext/core/Classes/Html/HtmlParser.php
index 25467b273c58d5aeaf4797d033dd62a9650a7e29..f3254889e4aed91e7c5251ac9fd17b6ee5e552a7 100644
--- a/typo3/sysext/core/Classes/Html/HtmlParser.php
+++ b/typo3/sysext/core/Classes/Html/HtmlParser.php
@@ -844,7 +844,7 @@ class HtmlParser {
 													if (!empty($newClasses)) {
 														$tagAttrib[0][$attr] = implode(' ', $newClasses);
 													} else {
-														$tagAttrib[0][$attr] = '';
+														$tagAttrib[0][$attr] = $params['list'][0];
 													}
 												} else {
 													if (!in_array($this->caseShift($tagAttrib[0][$attr], $params['casesensitiveComp']), $this->caseShift($params['list'], $params['casesensitiveComp'], $tagName))) {
diff --git a/typo3/sysext/core/Documentation/Changelog/master/Breaking-24186-HTMLparser-FixAttribclasslistDoesNotAssignFirstElementWhenAttributeValueNotInList.rst b/typo3/sysext/core/Documentation/Changelog/master/Breaking-24186-HTMLparser-FixAttribclasslistDoesNotAssignFirstElementWhenAttributeValueNotInList.rst
new file mode 100644
index 0000000000000000000000000000000000000000..c267c1a728cd4b7aae9c3095219347e966d62d43
--- /dev/null
+++ b/typo3/sysext/core/Documentation/Changelog/master/Breaking-24186-HTMLparser-FixAttribclasslistDoesNotAssignFirstElementWhenAttributeValueNotInList.rst
@@ -0,0 +1,18 @@
+Breaking: #24186 - HTMLparser - fixAttrib.['class'].list does not assign first element, when attribute value not in list
+=========================================================================================================================
+
+Description
+===========
+
+The HTMLparser now assigns the first class of ``fixAttrib.class.list`` when none of the given class name values
+are found in the configured list. Until now the class attribute of the rendered HTMl tag was just empty in that case.
+
+Impact
+======
+
+A HTMl element that had no class before could now have been assigned a class.
+
+Migration
+=========
+
+Add a class from the configured list to the HTML element or add a class at the first position of ``fixAttrib.class.list``.