core/modules/big_pipe/src/Render/BigPipe.php | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/core/modules/big_pipe/src/Render/BigPipe.php b/core/modules/big_pipe/src/Render/BigPipe.php
index 5e3cc12..16c862a 100644
--- a/core/modules/big_pipe/src/Render/BigPipe.php
+++ b/core/modules/big_pipe/src/Render/BigPipe.php
@@ -126,7 +126,11 @@ public function sendContent($content, array $attachments) {
     // Reopen it for the duration that we are rendering placeholders.
     $this->session->start();
 
-    list($pre_body, $post_body) = explode('</body>', $content, 2);
+    // Find the closing </body> tag and get the strings before and after. But be
+    // careful to use the latest occurrence of the string "</body>", to ensure
+    // that strings in inline JavaScript or CDATA sections aren't used instead.
+    list($pre_body, $post_body) = array_reverse(array_map('strrev', explode(strrev('</body>'), strrev($content), 2)));
+
     $this->sendPreBody($pre_body, $nojs_placeholders, $cumulative_assets);
     $this->sendPlaceholders($placeholders, $this->getPlaceholderOrder($pre_body), $cumulative_assets);
     $this->sendPostBody($post_body);