fix: reject noncanonical release archive paths

scripts/first_kill.py

@@ -132,13 +132,16 @@ def validated_zip_members(bundle: zipfile.ZipFile) -> list[zipfile.ZipInfo]:
     total = 0
     for member in members:
         name = member.filename
-        path = PurePosixPath(name)
+        raw_name = name.removesuffix("/")
+        raw_parts = raw_name.split("/")
+        path = PurePosixPath(raw_name)
         parts = path.parts
         normalized = path.as_posix().rstrip("/")
         if (
             not name
             or "\x00" in name
             or "\\" in name
+            or any(part in ("", ".", "..") for part in raw_parts)
             or path.is_absolute()
             or not normalized
             or any(part in ("", ".", "..") for part in parts)

scripts/verify_release.py

@@ -58,13 +58,16 @@ def validated_members(archive: zipfile.ZipFile) -> list[zipfile.ZipInfo]:
     total = 0
     for member in members:
         name = member.filename
-        path = PurePosixPath(name)
+        raw_name = name.removesuffix("/")
+        raw_parts = raw_name.split("/")
+        path = PurePosixPath(raw_name)
         parts = path.parts
         normalized = path.as_posix().rstrip("/")
         if (
             not name
             or "\x00" in name
             or "\\" in name
+            or any(part in ("", ".", "..") for part in raw_parts)
             or path.is_absolute()
             or not normalized
             or any(part in ("", ".", "..") for part in parts)

tests/test_first_kill.py

@@ -254,6 +254,16 @@ class FirstKillTests(unittest.TestCase):
             with self.assertRaisesRegex(first_kill.FirstKillError, "unsafe path"):
                 first_kill.safe_extract(archive, root / "out")
 
+    def test_safe_extract_rejects_noncanonical_components(self) -> None:
+        for member_name in ("release/./install.py", "release//install.py"):
+            with self.subTest(member_name=member_name), tempfile.TemporaryDirectory() as raw:
+                root = Path(raw)
+                archive = root / "noncanonical.zip"
+                with zipfile.ZipFile(archive, "w") as bundle:
+                    bundle.writestr(member_name, "untrusted")
+                with self.assertRaisesRegex(first_kill.FirstKillError, "unsafe path"):
+                    first_kill.safe_extract(archive, root / "out")
+
     def test_safe_extract_rejects_duplicate_paths(self) -> None:
         with tempfile.TemporaryDirectory() as raw:
             root = Path(raw)

tests/test_release_archive.py

@@ -66,6 +66,18 @@ class ReleaseArchiveTests(unittest.TestCase):
             ):
                 verify_release.validated_members(archive)
 
+    def test_verifier_rejects_noncanonical_components(self) -> None:
+        for member_name in ("release/./install.py", "release//install.py"):
+            with self.subTest(member_name=member_name), tempfile.TemporaryDirectory() as raw:
+                archive_path = Path(raw) / "noncanonical.zip"
+                with zipfile.ZipFile(archive_path, "w") as archive:
+                    archive.writestr(member_name, "untrusted")
+                with (
+                    zipfile.ZipFile(archive_path) as archive,
+                    self.assertRaisesRegex(SystemExit, "unsafe path"),
+                ):
+                    verify_release.validated_members(archive)
+
     def test_verifier_rejects_special_members(self) -> None:
         with tempfile.TemporaryDirectory() as raw:
             archive_path = Path(raw) / "special.zip"