diff --git a/typo3/sysext/core/Classes/Html/HtmlParser.php b/typo3/sysext/core/Classes/Html/HtmlParser.php
index ed1f3fecb3ccfcf6ae903ef52be7c0b00b759ab2..61be53dd7cf4f96346a009c7cb926e7d14ddd99b 100644
--- a/typo3/sysext/core/Classes/Html/HtmlParser.php
+++ b/typo3/sysext/core/Classes/Html/HtmlParser.php
@@ -454,7 +454,7 @@ class HtmlParser
                     $endTag = $firstChar === '/' ? 1 : 0;
                     $tagContent = substr($tok, $endTag, $tagEnd - $endTag);
                     $tagParts = preg_split('/\\s+/s', $tagContent, 2);
-                    $tagName = strtolower($tagParts[0]);
+                    $tagName = strtolower(rtrim($tagParts[0], '/'));
                     $emptyTag = 0;
                     if (isset($tags[$tagName])) {
                         // If there is processing to do for the tag:
diff --git a/typo3/sysext/core/Tests/Unit/Html/HtmlParserTest.php b/typo3/sysext/core/Tests/Unit/Html/HtmlParserTest.php
index 9f99539a51bc19227f4ca1ed6748c6972f5d1423..65bc60c57bf0b96c9e9ee2ef41a2eb0293e94b2e 100644
--- a/typo3/sysext/core/Tests/Unit/Html/HtmlParserTest.php
+++ b/typo3/sysext/core/Tests/Unit/Html/HtmlParserTest.php
@@ -152,6 +152,28 @@ class HtmlParserTest extends UnitTestCase
         self::assertSame($expected, $result);
     }
 
+    /**
+     * @test
+     * @dataProvider htmlWithDifferentSingleTagsDataProvider
+     */
+    public function htmlCleanerKeepsSingleTagsWithAndWithoutEndingSlashUnchanged(string $exampleString): void
+    {
+        $result = $this->subject->HTMLcleaner($exampleString, ['br' => true], 0);
+        self::assertSame($exampleString, $result);
+    }
+
+    /**
+     * Data provider for htmlCleanerCanHandleSingleTagsWithEndingSlashes
+     */
+    public static function htmlWithDifferentSingleTagsDataProvider(): array
+    {
+        return [
+            'no slash' => ['one<br>two'],
+            'slash without space' => ['one<br/>two'],
+            'space and slash' => ['one<br />two'],
+        ];
+    }
+
     /**
      * Data provider for spanTagCorrectlyRemovedWhenRmTagIfNoAttribIsConfigured
      */