diff --git a/chrome/browser/ui/views/digital_credentials/digital_identity_safety_interstitial_controller_desktop.cc b/chrome/browser/ui/views/digital_credentials/digital_identity_safety_interstitial_controller_desktop.cc
index 462aebd0d0648..2bae1d0449fcb 100644
--- a/chrome/browser/ui/views/digital_credentials/digital_identity_safety_interstitial_controller_desktop.cc
+++ b/chrome/browser/ui/views/digital_credentials/digital_identity_safety_interstitial_controller_desktop.cc
@@ -171,11 +171,20 @@ void DigitalIdentitySafetyInterstitialControllerDesktop::ShowInterstitialImpl(
   }
   dialog_widget_ = constrained_window::ShowWebModal(
       dialog_model_builder.Build(), &web_contents);
+  // ShowWebModal() can synchronously re-enter (via SetWebContentsBlocked →
+  // ExitFullscreen, which on some platforms spins a nested run loop) and
+  // destroy `web_contents`. `this` survives because `callback_` (which owns
+  // the controller) is only run via PostTask in OnDialogClosed(), but the
+  // by-reference `web_contents` parameter may now dangle. Re-check the
+  // WeakPtr captured in ShowInterstitial() before any further use.
+  if (!web_contents_) {
+    return;
+  }
   extensions::SecurityDialogTracker::GetInstance()->AddSecurityDialog(
       dialog_widget_);
 
   close_on_navigation_observer_ = std::make_unique<CloseOnNavigationObserver>();
-  close_on_navigation_observer_->Observe(web_contents);
+  close_on_navigation_observer_->Observe(*web_contents_);
 }
 
 void DigitalIdentitySafetyInterstitialControllerDesktop::OnDialogClosed(