Reject abbreviated forms of unsafe git options

git/cmd.py

@@ -967,11 +967,20 @@ def check_unsafe_options(cls, options: List[str], unsafe_options: List[str]) ->
         arbitrary commands. These are blocked by default.
         """
         # Options can be of the form `foo`, `--foo`, `--foo bar`, or `--foo=bar`.
+        # Git accepts any unambiguous prefix of a long option, so an abbreviated
+        # spelling such as `--upl` for `--upload-pack` must be rejected too. An
+        # option is unsafe if its canonical name is a prefix of any blocked
+        # option's canonical name.
         canonical_unsafe_options = {cls._canonicalize_option_name(option): option for option in unsafe_options}
         for option in options:
-            unsafe_option = canonical_unsafe_options.get(cls._canonicalize_option_name(option))
-            if unsafe_option is not None:
-                raise UnsafeOptionError(f"{unsafe_option} is not allowed, use `allow_unsafe_options=True` to allow it.")
+            candidate = cls._canonicalize_option_name(option)
+            if not candidate:
+                continue
+            for canonical, unsafe_option in canonical_unsafe_options.items():
+                if canonical.startswith(candidate):
+                    raise UnsafeOptionError(
+                        f"{unsafe_option} is not allowed, use `allow_unsafe_options=True` to allow it."
+                    )
 
     AutoInterrupt: TypeAlias = _AutoInterrupt
 

test/test_clone.py

@@ -138,6 +138,21 @@ def test_clone_unsafe_options(self, rw_repo):
                     rw_repo.clone(tmp_dir, **unsafe_option)
                 assert not tmp_file.exists()
 
+    @with_rw_repo("HEAD")
+    def test_clone_unsafe_options_abbreviated(self, rw_repo):
+        with tempfile.TemporaryDirectory() as tdir:
+            tmp_dir = pathlib.Path(tdir)
+            tmp_file = tmp_dir / "pwn"
+            unsafe_options = [
+                f"--upl='touch {tmp_file}'",
+                f"--upload-pac='touch {tmp_file}'",
+                "--conf=protocol.ext.allow=always",
+            ]
+            for unsafe_option in unsafe_options:
+                with self.assertRaises(UnsafeOptionError):
+                    rw_repo.clone(tmp_dir, multi_options=[unsafe_option])
+                assert not tmp_file.exists()
+
     @with_rw_repo("HEAD")
     def test_clone_unsafe_options_are_checked_after_splitting_multi_options(self, rw_repo):
         with tempfile.TemporaryDirectory() as tdir: