diff --git a/scripts/ci/sandboxed_web_e2e.py b/scripts/ci/sandboxed_web_e2e.py
index 1be073104a..b0376c0822 100644
--- a/scripts/ci/sandboxed_web_e2e.py
+++ b/scripts/ci/sandboxed_web_e2e.py
@@ -221,7 +221,8 @@ def _probe_isolation_capability(backend: str) -> None:
             "--dev",
             "/dev",
             "--tmpfs",
-            "/tmp",
+            # This is the isolated namespace's tmpfs target, not a host temp path.
+            "/tmp",  # nosec B108  # noqa: S108
             "--bind",
             probe_workspace,
             SANDBOX_MOUNT,
@@ -432,7 +433,8 @@ def isolated_command(
             "--dev",
             "/dev",
             "--tmpfs",
-            "/tmp",
+            # This is the isolated namespace's tmpfs target, not a host temp path.
+            "/tmp",  # nosec B108  # noqa: S108
             "--bind",
             str(sandbox_root),
             SANDBOX_MOUNT,
@@ -546,7 +548,7 @@ def require_unoccupied_readiness_port(url: str) -> None:
     """
     parsed = urllib.parse.urlparse(url)
     hostname = parsed.hostname or "127.0.0.1"
-    port = parsed.port or (443 if parsed.scheme.lower() == "https" else 80)
+    port = parsed.port if parsed.port is not None else (443 if parsed.scheme.lower() == "https" else 80)
     try:
         with socket.create_connection((hostname, port), timeout=0.2):
             pass
diff --git a/tests/test_sandboxed_web_e2e.py b/tests/test_sandboxed_web_e2e.py
index 4ab489c179..1b1cdf3722 100644
--- a/tests/test_sandboxed_web_e2e.py
+++ b/tests/test_sandboxed_web_e2e.py
@@ -464,6 +464,50 @@ def test_require_unoccupied_readiness_port_allows_a_free_port():
     sandboxed_web_e2e.require_unoccupied_readiness_port(f"http://127.0.0.1:{port}/health")
 
 
+def test_require_unoccupied_readiness_port_probes_explicit_port_zero(monkeypatch):
+    """An explicit ``:0`` port must be probed as port 0, not the scheme default.
+
+    ``urllib.parse``'s ``.port`` returns the int ``0`` for a URL with an
+    explicit ``:0`` port, and ``0 or 80`` evaluates to ``80`` in Python, so a
+    naive ``parsed.port or <default>`` derivation silently probes the
+    scheme's default port instead of the requested port 0. Devin's review on
+    PR #1347 flagged this pattern. This regression test records the actual
+    address ``require_unoccupied_readiness_port`` probes and asserts it names
+    port 0, not port 80, pinning the ``parsed.port if parsed.port is not
+    None else <default>`` fix.
+    """
+    recorded = []
+
+    def fake_create_connection(address, timeout):
+        recorded.append(address)
+        raise OSError("nothing listening")
+
+    monkeypatch.setattr(sandboxed_web_e2e.socket, "create_connection", fake_create_connection)
+
+    sandboxed_web_e2e.require_unoccupied_readiness_port("http://127.0.0.1:0/health")
+
+    assert recorded == [("127.0.0.1", 0)]
+
+
+def test_bubblewrap_tmpfs_targets_have_only_targeted_bandit_waivers():
+    """B108/S108 waivers cover only bubblewrap's isolated tmpfs mount targets.
+
+    These strings are command arguments naming the mount point created inside
+    the new bubblewrap namespace; they are not host temporary-file paths. A
+    targeted waiver keeps Bandit's and Ruff's real host-path checks enabled
+    everywhere else while preventing these two deliberate mount targets from
+    blocking the Python security gate or the lint gate.
+    """
+    source = Path(sandboxed_web_e2e.__file__).read_text(encoding="utf-8")
+    waiver = '"/tmp",  # nosec B108  # noqa: S108'
+    rationale = "isolated namespace's tmpfs target, not a host temp path"
+
+    assert source.count(waiver) == 2
+    assert source.count("nosec B108") == 2
+    assert source.count("noqa: S108") == 2
+    assert source.count(rationale) == 2
+
+
 def test_main_reports_occupied_readiness_port_before_starting_services(monkeypatch, tmp_path, capsys):
     """A readiness port already occupied by another process fails closed with exit 125."""
     repo = tmp_path / "repo"