diff --git a/tests/entrypoints/serve/utils/test_error_sanitization.py b/tests/entrypoints/serve/utils/test_error_sanitization.py
new file mode 100644
index 0000000000..c871dffb40
--- /dev/null
+++ b/tests/entrypoints/serve/utils/test_error_sanitization.py
@@ -0,0 +1,81 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""Tests that error messages in Anthropic and speech-to-text entrypoints
+are sanitized to prevent memory address leakage.
+
+Verifies the fix for the incomplete CVE-2026-22778 remediation where
+PIL repr addresses leaked via the Anthropic API router and the
+speech-to-text WebSocket paths.
+"""
+
+import pytest
+
+from vllm.entrypoints.serve.utils.api_utils import sanitize_message
+
+
+class TestSanitizeMessageCoversLeakPatterns:
+    """Ensure sanitize_message strips addresses from realistic exceptions."""
+
+    @pytest.mark.parametrize(
+        ("raw", "expected"),
+        [
+            (
+                "cannot identify image file <_io.BytesIO object at 0x7a95e299e750>",
+                "cannot identify image file <_io.BytesIO object>",
+            ),
+            (
+                "cannot identify image file <_io.BytesIO object at 0x7f3c1a2b4d90>",
+                "cannot identify image file <_io.BytesIO object>",
+            ),
+            (
+                "<PIL.PngImagePlugin.PngImageFile image mode=RGB "
+                "size=8x8 at 0x7f3c1a2b4d90>",
+                "<PIL.PngImagePlugin.PngImageFile image mode=RGB size=8x8>",
+            ),
+            (
+                "Error processing <_io.BytesIO object at 0xdeadbeef>: invalid header",
+                "Error processing <_io.BytesIO object>: invalid header",
+            ),
+        ],
+        ids=[
+            "bytesio-standard",
+            "bytesio-different-addr",
+            "pil-image-repr",
+            "mid-string-repr",
+        ],
+    )
+    def test_address_stripped(self, raw: str, expected: str):
+        assert sanitize_message(raw) == expected
+
+    def test_safe_message_unchanged(self):
+        msg = "Invalid request: missing 'messages' field"
+        assert sanitize_message(msg) == msg
+
+    def test_multiple_addresses_stripped(self):
+        raw = "<obj at 0xaaa> and <obj at 0xbbb>"
+        result = sanitize_message(raw)
+        assert "0x" not in result
+
+
+class TestAffectedModulesUseSanitize:
+    """Verify that affected modules call sanitize_message (source-level)."""
+
+    @pytest.mark.parametrize(
+        "module",
+        [
+            "vllm.entrypoints.anthropic.api_router",
+            "vllm.entrypoints.anthropic.serving",
+            "vllm.entrypoints.speech_to_text.realtime.connection",
+        ],
+    )
+    def test_module_calls_sanitize_message(self, module: str):
+        import importlib.util
+        from pathlib import Path
+
+        spec = importlib.util.find_spec(module)
+        assert spec is not None and spec.origin is not None, (
+            f"Cannot locate module {module}"
+        )
+        source = Path(spec.origin).read_text()
+        assert "sanitize_message" in source, f"{module} does not call sanitize_message"
+        assert "import" in source and "sanitize_message" in source
diff --git a/vllm/entrypoints/anthropic/api_router.py b/vllm/entrypoints/anthropic/api_router.py
index 50a8dae9ec..16756a9028 100644
--- a/vllm/entrypoints/anthropic/api_router.py
+++ b/vllm/entrypoints/anthropic/api_router.py
@@ -19,6 +19,7 @@ from vllm.entrypoints.anthropic.serving import AnthropicServingMessages
 from vllm.entrypoints.openai.engine.protocol import ErrorResponse
 from vllm.entrypoints.serve.utils.api_utils import (
     load_aware_call,
+    sanitize_message,
     validate_json_request,
     with_cancellation,
 )
@@ -75,7 +76,7 @@ async def create_messages(request: AnthropicMessagesRequest, raw_request: Reques
             content=AnthropicErrorResponse(
                 error=AnthropicError(
                     type="internal_error",
-                    message=str(e),
+                    message=sanitize_message(str(e)),
                 )
             ).model_dump(),
         )
@@ -121,7 +122,7 @@ async def count_tokens(request: AnthropicCountTokensRequest, raw_request: Reques
             content=AnthropicErrorResponse(
                 error=AnthropicError(
                     type="internal_error",
-                    message=str(e),
+                    message=sanitize_message(str(e)),
                 )
             ).model_dump(),
         )
diff --git a/vllm/entrypoints/anthropic/serving.py b/vllm/entrypoints/anthropic/serving.py
index 806261b597..8f6cccdb0f 100644
--- a/vllm/entrypoints/anthropic/serving.py
+++ b/vllm/entrypoints/anthropic/serving.py
@@ -44,6 +44,7 @@ from vllm.entrypoints.openai.engine.protocol import (
     StreamOptions,
 )
 from vllm.entrypoints.openai.models.serving import OpenAIServingModels
+from vllm.entrypoints.serve.utils.api_utils import sanitize_message
 from vllm.entrypoints.serve.utils.request_logger import RequestLogger
 
 if TYPE_CHECKING:
@@ -846,7 +847,9 @@ class AnthropicServingMessages(OpenAIServingChat):
             logger.exception("Error in message stream converter.")
             error_response = AnthropicStreamEvent(
                 type="error",
-                error=AnthropicError(type="internal_error", message=str(e)),
+                error=AnthropicError(
+                    type="internal_error", message=sanitize_message(str(e))
+                ),
             )
             data = error_response.model_dump_json(exclude_unset=True)
             yield wrap_data_with_event(data, "error")
diff --git a/vllm/entrypoints/speech_to_text/realtime/connection.py b/vllm/entrypoints/speech_to_text/realtime/connection.py
index c7d1af9299..32f501f104 100644
--- a/vllm/entrypoints/speech_to_text/realtime/connection.py
+++ b/vllm/entrypoints/speech_to_text/realtime/connection.py
@@ -14,6 +14,7 @@ from starlette.websockets import WebSocketDisconnect
 
 from vllm import envs
 from vllm.entrypoints.openai.engine.protocol import ErrorResponse, UsageInfo
+from vllm.entrypoints.serve.utils.api_utils import sanitize_message
 from vllm.exceptions import VLLMValidationError
 from vllm.logger import init_logger
 
@@ -72,7 +73,7 @@ class RealtimeConnection:
                     await self.send_error("Invalid JSON", "invalid_json")
                 except Exception as e:
                     logger.exception("Error handling event: %s", e)
-                    await self.send_error(str(e), "processing_error")
+                    await self.send_error(sanitize_message(str(e)), "processing_error")
         except WebSocketDisconnect:
             logger.debug("WebSocket disconnected: %s", self.connection_id)
             self._is_connected = False
@@ -262,7 +263,7 @@ class RealtimeConnection:
 
         except Exception as e:
             logger.exception("Error in generation: %s", e)
-            await self.send_error(str(e), "processing_error")
+            await self.send_error(sanitize_message(str(e)), "processing_error")
 
     async def send(
         self, event: SessionCreated | TranscriptionDelta | TranscriptionDone