From 7a96ea666c6f5f9c71b7fe305860ec43c8e929cd Mon Sep 17 00:00:00 2001
From: Sascha Weidner <support@sioweb.de>
Date: Sat, 28 Mar 2026 19:26:33 +0100
Subject: [PATCH] Update Resizer.php

Prevent animated GIF endless loop (Error 502)
---
 src/Resizer.php | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/src/Resizer.php b/src/Resizer.php
index f21b90a..f125068 100644
--- a/src/Resizer.php
+++ b/src/Resizer.php
@@ -247,6 +247,10 @@ protected function processResize(ImageInterface $image, ResizeConfiguration $con
             return $this->createImage($image, $image->getPath());
         }
 
+        if ($this->isAnimatedGif($image->getPath())) {
+            return $this->createImage($image, $image->getPath());
+        }
+
         $cachePath = Path::join($this->cacheDir, $this->createCachePath($image->getPath(), $coordinates, $options, false));
 
         if (!$options->getBypassCache()) {
@@ -365,4 +369,30 @@ private function encodeBase32(string $bytes): string
 
         return implode('', $result);
     }
+
+    /**
+     * Check if a file is an animated GIF.
+     */
+    private function isAnimatedGif(string $path): bool
+    {
+        if (strtolower(pathinfo($path, PATHINFO_EXTENSION)) !== 'gif') {
+            return false;
+        }
+
+        if (!file_exists($path)) {
+            return false;
+        }
+
+        $content = file_get_contents($path, false, null, 0, 3145728);
+
+        if ($content === false) {
+            return false;
+        }
+
+        // Count occurrences of the GIF image separator byte
+        // Animated GIFs have multiple image blocks (0x00,0x21,0xF9)
+        $count = preg_match_all('#\x00\x21\xF9\x04#', $content, $matches);
+
+        return $count > 1;
+    }
 }