diff --git a/web/app.js b/web/app.js
index 8c77243d9..72019cabd 100644
--- a/web/app.js
+++ b/web/app.js
@@ -943,6 +943,13 @@ const PDFViewerApplication = {
     this.pdfLoadingTask = loadingTask;
 
     loadingTask.onPassword = (updateCallback, reason) => {
+      if (this.isViewerEmbedded) {
+        // The load event can't be triggered until the password is entered, so
+        // if the viewer is in an iframe and its visibility depends on the
+        // onload callback then the viewer never shows (bug 1801341).
+        this._unblockDocumentLoadEvent();
+      }
+
       this.pdfLinkService.externalLinkEnabled = false;
       this.passwordPrompt.setUpdateCallback(updateCallback, reason);
       this.passwordPrompt.open();