diff --git a/third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc b/third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc
index 5eb728dfec5b9..32616bc8b47f0 100644
--- a/third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc
+++ b/third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc
@@ -988,8 +988,21 @@ ScriptPromise<IDLUndefined> WebGLRenderingContextBase::makeXRCompatible(
     return ToResolvedUndefinedPromise(script_state);
 
   // If there's a request currently in progress, return the same promise.
-  if (make_xr_compatible_resolver_)
+  if (make_xr_compatible_resolver_) {
+    // The cached resolver is bound to the world that initiated the original
+    // request. Returning its v8::Promise to a caller from a different world
+    // would leak a cross-world JS object and break isolated-world isolation.
+    // Reject in the caller's world instead.
+    if (&make_xr_compatible_resolver_->GetScriptState()->World() !=
+        &script_state->World()) {
+      exception_state.ThrowDOMException(
+          DOMExceptionCode::kInvalidStateError,
+          "A makeXRCompatible request from another execution world is already "
+          "in progress.");
+      return EmptyPromise();
+    }
     return make_xr_compatible_resolver_->Promise();
+  }
 
   make_xr_compatible_resolver_ =
       MakeGarbageCollected<ScriptPromiseResolver<IDLUndefined>>(