diff --git a/packages/lib/server-only/pdf/get-page-size.ts b/packages/lib/server-only/pdf/get-page-size.ts
index 8c88912b0..982810f1d 100644
--- a/packages/lib/server-only/pdf/get-page-size.ts
+++ b/packages/lib/server-only/pdf/get-page-size.ts
@@ -13,14 +13,31 @@ const MIN_CERT_PAGE_HEIGHT = 300;
  * Falls back to MediaBox when it's smaller than CropBox, following typical PDF reader behavior.
  */
 export const getPageSize = (page: PDFPage) => {
-  const cropBox = page.getCropBox();
-  const mediaBox = page.getMediaBox();
+  let mediaBox;
+  let cropBox;
 
-  if (mediaBox.width < cropBox.width || mediaBox.height < cropBox.height) {
-    return mediaBox;
+  try {
+    mediaBox = page.getMediaBox();
+  } catch {
+    // MediaBox lookup can fail for malformed PDFs where the entry is not a valid PDFArray.
   }
 
-  return cropBox;
+  try {
+    cropBox = page.getCropBox();
+  } catch {
+    // CropBox lookup can fail for malformed PDFs where the entry is not a valid PDFArray.
+  }
+
+  if (mediaBox && cropBox) {
+    if (mediaBox.width < cropBox.width || mediaBox.height < cropBox.height) {
+      return mediaBox;
+    }
+
+    return cropBox;
+  }
+
+  // If either box is missing or invalid, fall back to MediaBox if available, otherwise CropBox, or default to A4 size.
+  return mediaBox || cropBox || PDF_SIZE_A4_72PPI;
 };
 
 export const getLastPageDimensions = (pdfDoc: PDF): { width: number; height: number } => {