Filter out `null` values passed as BBCode attribute

See https://www.woltlab.com/community/thread/303836/

diff --git a/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php b/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
index eef1fb56a867ce26d5c6c469ab0ed9e05c3eb94c..93f6a437d62ed5085d222f16ebc081f4604ba3bf 100644 (file)
--- a/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
@@ -354,6 +354,8 @@ class HtmlBBCodeParser extends BBCodeParser
      */
     public function buildBBCodeTag($name, $attributes, $openingTagOnly = false)
     {
+        $attributes = \array_filter($attributes, fn ($value) => $value !== null);
+
         if (!empty($attributes)) {
             foreach ($attributes as &$attribute) {
                 $attribute = "'" . \addcslashes($attribute, "'") . "'";