diff --git a/backend/tests/test_provisioner_request_threading.py b/backend/tests/test_provisioner_request_threading.py
index 933b2ad61..676292991 100644
--- a/backend/tests/test_provisioner_request_threading.py
+++ b/backend/tests/test_provisioner_request_threading.py
@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import asyncio
 import inspect
+import logging
 import threading
 import time
 from contextlib import contextmanager
@@ -42,6 +43,34 @@ def test_provisioner_accepts_canonical_thread_ids(provisioner_module, thread_id:
     assert request.thread_id == thread_id
 
 
+def test_sandbox_access_url_sanitizes_transient_error_log(
+    caplog: pytest.LogCaptureFixture,
+    monkeypatch: pytest.MonkeyPatch,
+    provisioner_module,
+) -> None:
+    class FailingCoreV1:
+        def read_namespaced_service(self, _name: str, _namespace: str):
+            raise ApiException(status=500, reason="upstream\nforged\rentry")
+
+    monkeypatch.setattr(provisioner_module, "core_v1", FailingCoreV1())
+    caplog.set_level(logging.WARNING, logger=provisioner_module.logger.name)
+
+    assert (
+        provisioner_module._sandbox_access_url(
+            "sandbox\nforged",
+            tolerate_read_errors=True,
+        )
+        is None
+    )
+
+    assert len(caplog.records) == 1
+    message = caplog.records[0].getMessage()
+    assert "sandboxforged" in message
+    assert "upstreamforgedentry" in message
+    assert "\n" not in message
+    assert "\r" not in message
+
+
 def test_create_rejects_mount_contract_precondition_before_k8s_io(
     monkeypatch: pytest.MonkeyPatch,
     provisioner_module,
diff --git a/backend/tests/test_upload_sandbox_sync.py b/backend/tests/test_upload_sandbox_sync.py
index 8ac8d6873..348fdc731 100644
--- a/backend/tests/test_upload_sandbox_sync.py
+++ b/backend/tests/test_upload_sandbox_sync.py
@@ -420,7 +420,7 @@ def test_failed_journal_restore_keeps_cross_process_name_reservation(tmp_path):
             raise OSError("directory fsync failed")
         return real_fsync(descriptor)
 
-    def fail_journal_recreation(path, flags, mode=0o777):
+    def fail_journal_recreation(path, flags, mode=0o600):
         if os.path.abspath(path) == os.path.abspath(journal_path) and flags & os.O_CREAT:
             raise OSError("journal recreation failed")
         return real_open(path, flags, mode)
diff --git a/docker/provisioner/app.py b/docker/provisioner/app.py
index 288670a36..3d76015be 100644
--- a/docker/provisioner/app.py
+++ b/docker/provisioner/app.py
@@ -58,6 +58,12 @@ logging.basicConfig(
     format="%(asctime)s [%(levelname)s] %(name)s: %(message)s",
 )
 
+
+def _sanitize_log_param(value: object) -> str:
+    """Strip line-breaking controls from values before logging them."""
+    return str(value).replace("\r", "").replace("\n", "").replace("\x00", "")
+
+
 # ── Configuration (all tuneable via environment variables) ───────────────
 
 K8S_NAMESPACE = os.environ.get("K8S_NAMESPACE", "deer-flow")
@@ -1290,9 +1296,9 @@ def _sandbox_access_url(
         if tolerate_read_errors and exc.status not in {401, 403}:
             logger.warning(
                 "Transient error reading Service %s: status=%s reason=%s",
-                _svc_name(sandbox_id),
-                exc.status,
-                exc.reason,
+                _sanitize_log_param(_svc_name(sandbox_id)),
+                _sanitize_log_param(exc.status),
+                _sanitize_log_param(exc.reason),
             )
             return None
         raise