WordPress Started Executing Code Inside PRE Tags Even They Are Properly Escaped

Question

Note: I am using https://wordpress.org/plugins/classic-editor/ with latest updated WordPress.

I have a Blog at https://www.exeideas.com/ and I share code snippet here also that was working before perfectly as I share the Escaped Codes inside <pre> and <code> tag but suddenly it started executing codes inside the <pre> and <code> tags all over my blog for example at https://www.exeideas.com/2022/10/responsive-collapsible-sidebar-and-tab-nav.html

It was working till yesterday. Any way to fix this all over my blog where I have about 3800+ articles that contain <pre> and <code> tags, I tried the following solutions but was not successful...

functions.php

add_filter( 'the_content', 'pre_content_filter', 0 );
function pre_content_filter( $content ) {
    return preg_replace_callback( '|<pre.*>(.*)</pre|isU' , 'convert_pre_entities', $content );
}
function convert_pre_entities( $matches ) {
    return str_replace( $matches[1], html_entity_decode( $matches[1] ), $matches[0] );
}

functions.php

add_filter('the_content','pre_esc_html',9);
function pre_esc_html($content) {
  return preg_replace_callback(
    '#(<pre.*?>)(.*?)(</pre>)#imsu',
    create_function(
      '$i',
      'return $i[1].esc_html($i[2]).$i[3];'
    ),
    $content
  );
}

single.php

<?php
function escapeRecursively($node) {
    if ($node instanceof DOMText)
        return $node->textContent;

    $children = $node->childNodes;
    $content = "<$node->nodeName>";
    for ($i = 0; $i < $children->length; $i += 1) {
        $child = $children->item($i);
        $content .= escapeRecursively($child);
    }

    return "$content</$node->nodeName>";
}
function escapePreformattedCode($html) {
    $doc = new DOMDocument();
    $doc->loadHTML($html);

    $pres = $doc->getElementsByTagName('pre');
    for ($i = 0; $i < $pres->length; $i += 1) {
        $node = $pres->item($i);

        $children = $node->childNodes;
        $content = '';
        for ($j = 0; $j < $children->length; $j += 1) {
            $child = $children->item($j);
            $content .= escapeRecursively($child);
        }
        $node->nodeValue = htmlspecialchars($content);
    }

    return $doc->saveHTML();
}   
?>
<div class="post">  
<?php echo escapePreformattedCode(the_content()); ?>
<div class="clear"></div>
</div>

But none of this is working. This happen to all of my old posts too that were working yesterday. What were the fix to it and avoid editing all 3800+ posts...

Answer 1

Quick Fix Answer:

---

Add the below code to your theme functions.php file for a quick fix. Rest still trying to find the reason for this error so if you have any then welcome to comment here so I will mark your answer as accepted.

/* ------------------------------------------------------------------------- *
 *  Stop Executing Codes Inside Pre/Code Tags
/* ------------------------------------------------------------------------- */
add_filter('the_content','pre_esc_html',1);
function pre_esc_html($content) {
    return preg_replace_callback(
    '#(<pre.*?>)(.*?)(</pre>)#imsu',
    create_function(
      '$i',
      'return $i[1].htmlspecialchars($i[2]).$i[3];'
    ),
    $content
  );
}

add_filter('the_content','code_esc_html',1);
function code_esc_html($content) {
    return preg_replace_callback(
    '#(<code.*?>)(.*?)(</code>)#imsu',
    create_function(
      '$i',
      'return $i[1].htmlspecialchars($i[2]).$i[3];'
    ),
    $content
  );
}