fix(deps): require XXE-safe lxml

pyproject.toml

@@ -127,7 +127,11 @@ serve = [
     "msgpack>=1.0",
     "opencv-python-headless>=4.8",  # JPEG-on-wire serialization for ZMQ transport
 ]
-safety = ["yourdfpy"]
+safety = [
+    "yourdfpy",
+    # CVE-2026-41066: older iterparse defaults can resolve local-file entities.
+    "lxml>=6.1.0",
+]
 # Offline EU evidence-pack generator. No runtime deps today; kept as an extra
 # so pilots can install with `pip install fastcrest-tether[serve,comply]`.
 comply = []

tests/test_pyproject_metadata.py

@@ -5,6 +5,8 @@
 from pathlib import Path
 
 import pytest
+from packaging.requirements import Requirement
+from packaging.version import Version
 
 
 REPO_ROOT = Path(__file__).parent.parent
@@ -29,6 +31,25 @@ def test_serve_extra_installs_cpu_onnxruntime():
     )
 
 
+def test_safety_extra_requires_xxe_safe_lxml():
+    """Keep the URDF parser above the CVE-2026-41066 security floor."""
+    pyproject = _toml_loads((REPO_ROOT / "pyproject.toml").read_text())
+    safety_deps = pyproject["project"]["optional-dependencies"]["safety"]
+    requirements = {Requirement(dep).name: Requirement(dep) for dep in safety_deps}
+
+    assert "lxml" in requirements
+    assert str(requirements["lxml"].specifier) == ">=6.1.0"
+
+
+def test_lockfile_selects_xxe_safe_lxml():
+    """Frozen safety installs must not restore a vulnerable lxml release."""
+    lock = _toml_loads((REPO_ROOT / "uv.lock").read_text())
+    lxml_packages = [package for package in lock["package"] if package["name"] == "lxml"]
+
+    assert len(lxml_packages) == 1
+    assert Version(lxml_packages[0]["version"]) >= Version("6.1.0")
+
+
 def test_package_install_smoke_uploads_deploy_proof_packet():
     workflow = (REPO_ROOT / ".github/workflows/package-install-smoke.yml").read_text()