diff --git a/pyrit/backend/services/attack_service.py b/pyrit/backend/services/attack_service.py
index 1fc2821a37..9437632392 100644
--- a/pyrit/backend/services/attack_service.py
+++ b/pyrit/backend/services/attack_service.py
@@ -870,11 +870,14 @@ async def _persist_base64_pieces_async(request: AddMessageRequest) -> None:
                         piece.converted_value = file_path
                 continue
 
-            # Already an existing file on disk — keep as-is
-            if Path(piece.original_value).is_file():
-                if piece.converted_value is None:
-                    piece.converted_value = piece.original_value
-                continue
+            # Already an existing file on disk — keep as-is.
+            try:
+                if Path(piece.original_value).is_file():
+                    if piece.converted_value is None:
+                        piece.converted_value = piece.original_value
+                    continue
+            except (OSError, ValueError):
+                pass
 
             # Derive file extension from the MIME type sent by the frontend
             ext = None
diff --git a/tests/unit/backend/test_attack_service.py b/tests/unit/backend/test_attack_service.py
index f3e2e91a0c..11da01effe 100644
--- a/tests/unit/backend/test_attack_service.py
+++ b/tests/unit/backend/test_attack_service.py
@@ -1596,6 +1596,35 @@ async def test_non_path_data_types_are_skipped(self, attack_service) -> None:
 
         assert request.pieces[0].original_value == "thinking step"
 
+    @pytest.mark.asyncio
+    async def test_long_base64_audio_does_not_crash(self, attack_service) -> None:
+        """Base64 audio data longer than OS path limits should be saved, not crash with OSError."""
+        # Simulate a base64-encoded WAV file (>4096 chars, exceeds Linux filename limit of 255)
+        long_b64 = "UklGRiQ" + "A" * 5000  # fake WAV header + padding
+        request = AddMessageRequest(
+            role="user",
+            pieces=[
+                MessagePieceRequest(
+                    data_type="audio_path",
+                    original_value=long_b64,
+                    mime_type="audio/wav",
+                )
+            ],
+            send=False,
+            target_conversation_id="test-id",
+        )
+
+        with patch("pyrit.backend.services.attack_service.data_serializer_factory") as mock_factory:
+            mock_serializer = AsyncMock()
+            mock_serializer.value = "/tmp/saved_audio.wav"
+            mock_factory.return_value = mock_serializer
+
+            await AttackService._persist_base64_pieces_async(request)
+
+            mock_factory.assert_called_once()
+            mock_serializer.save_b64_image.assert_called_once_with(data=long_b64)
+            assert request.pieces[0].original_value == "/tmp/saved_audio.wav"
+
 
 # ============================================================================
 # Related Conversations Tests