diff --git a/backends/xnnpack/runtime/XNNCompiler.cpp b/backends/xnnpack/runtime/XNNCompiler.cpp
index 352d7af5a14..103bdeb6b82 100644
--- a/backends/xnnpack/runtime/XNNCompiler.cpp
+++ b/backends/xnnpack/runtime/XNNCompiler.cpp
@@ -319,6 +319,15 @@ Error defineTensor(
   ET_CHECK_OR_RETURN_ERROR(
       tensor_value != nullptr, InvalidProgram, "Deserialized tensor is null");
 
+  // Validate that tensor_value->flags() is a subset of the allowed flags.
+  constexpr uint32_t kAllowedFlagsMask =
+      XNN_VALUE_FLAG_EXTERNAL_INPUT | XNN_VALUE_FLAG_EXTERNAL_OUTPUT;
+  ET_CHECK_OR_RETURN_ERROR(
+      (tensor_value->flags() & ~kAllowedFlagsMask) == 0,
+      InvalidProgram,
+      "Tensor value has unsupported flag bits 0x%x",
+      tensor_value->flags());
+
   // Get tensor dims, here we need to use a vector in order to properly
   // convert the uint32_t* to size_t*. Scalar tensors (rank 0) are permitted
   // to have a null dims vector; in that case dims_data is empty.