diff --git a/mlir/lib/Bytecode/Reader/BytecodeReader.cpp b/mlir/lib/Bytecode/Reader/BytecodeReader.cpp
index 07a9266dcd1fa..caa17ea57b950 100644
--- a/mlir/lib/Bytecode/Reader/BytecodeReader.cpp
+++ b/mlir/lib/Bytecode/Reader/BytecodeReader.cpp
@@ -1503,6 +1503,7 @@ LogicalResult AttrTypeReader::parseCustomEntry(Entry<T> &entry,
     // Try parsing with callbacks first if available.
     for (const auto &callback :
          parserConfig.getBytecodeReaderConfig().getTypeCallbacks()) {
+      size_t savedWorklistSize = deferredWorklist.size();
       if (failed(
               callback->read(dialectReader, entry.dialect->name, entry.entry)))
         return failure();
@@ -1510,14 +1511,17 @@ LogicalResult AttrTypeReader::parseCustomEntry(Entry<T> &entry,
       if (!!entry.entry)
         return success();
 
-      // Reset the reader if we failed to parse, so we can fall through the
-      // other parsing functions.
+      // The callback fell through without consuming the encoding. Reset the
+      // reader and restore the deferred worklist: any entries added during the
+      // callback's partial read are stale and must not persist.
+      deferredWorklist.resize(savedWorklistSize);
       reader = EncodingReader(entry.data, reader.getLoc());
     }
   } else {
     // Try parsing with callbacks first if available.
     for (const auto &callback :
          parserConfig.getBytecodeReaderConfig().getAttributeCallbacks()) {
+      size_t savedWorklistSize = deferredWorklist.size();
       if (failed(
               callback->read(dialectReader, entry.dialect->name, entry.entry)))
         return failure();
@@ -1525,8 +1529,10 @@ LogicalResult AttrTypeReader::parseCustomEntry(Entry<T> &entry,
       if (!!entry.entry)
         return success();
 
-      // Reset the reader if we failed to parse, so we can fall through the
-      // other parsing functions.
+      // The callback fell through without consuming the encoding. Reset the
+      // reader and restore the deferred worklist: any entries added during the
+      // callback's partial read are stale and must not persist.
+      deferredWorklist.resize(savedWorklistSize);
       reader = EncodingReader(entry.data, reader.getLoc());
     }
   }
diff --git a/mlir/test/Bytecode/bytecode_callback_with_spirv_and_custom_attr.mlir b/mlir/test/Bytecode/bytecode_callback_with_spirv_and_custom_attr.mlir
new file mode 100644
index 0000000000000..e2bf0453f3f45
--- /dev/null
+++ b/mlir/test/Bytecode/bytecode_callback_with_spirv_and_custom_attr.mlir
@@ -0,0 +1,30 @@
+// RUN: mlir-opt %s --test-bytecode-roundtrip="test-kind=4" | FileCheck %s
+
+// Regression test for https://github.com/llvm/llvm-project/issues/163337
+//
+// When using test-kind=4, the attribute callback calls the builtin dialect
+// reader for each attribute. For dialect-specific attributes (e.g., spirv.*),
+// the builtin reader fails and the callback falls through to the regular reader.
+// During the failing read, the callback may add entries to the deferred parsing
+// worklist. These stale entries must be discarded when the reader position is
+// reset, otherwise the `deferredWorklist.empty()` assertion fires in debug
+// builds and may corrupt subsequent attribute resolution in release builds.
+
+spirv.module Logical GLSL450 {
+  spirv.func @callee() -> () "None" {
+    spirv.Kill
+  }
+  spirv.func @caller() -> () "None" {
+    spirv.FunctionCall @callee() : () -> ()
+    spirv.Return
+  }
+}
+
+// CHECK-LABEL: spirv.module Logical GLSL450
+// CHECK: spirv.func @callee
+// CHECK: spirv.func @caller
+
+// Verify the custom test attribute roundtrips correctly through the callback.
+"test.versionedC"() <{attribute = #test.attr_params<42, 24>}> : () -> ()
+
+// CHECK: "test.versionedC"() <{attribute = #test.attr_params<42, 24>}> : () -> ()