From c417af469f9aa3da8dfef78f996c0fb8c5d1f4c2 Mon Sep 17 00:00:00 2001 From: "GPT 5.5" Date: Wed, 29 Apr 2026 05:47:57 +0800 Subject: [PATCH 1/2] reject control chars in written values in configuration Reject CR, LF, and NUL in GitConfigParser values before writing them to git config files (which also is a deviation from Git which escapes them). GitConfigParser._write() serializes embedded newlines as indented continuation lines by replacing "\n" with "\n\t". Git itself skips leading whitespace before parsing config tokens, so an injected value such as: foo [core] hooksPath=/tmp/hooks is written in a form where the indented "[core]" line is still parsed by Git as a real section header. This lets attacker-controlled input passed to config_writer().set_value() poison repository config, including core.hooksPath, and redirect hook execution for later Git operations. Fail closed instead of stripping or normalizing these characters. Silent normalization can hide unsanitized caller input, and GitPython does not currently round-trip Git-style escaped values such as "\n" as embedded newlines. Apply the validation to set_value(), add_value(), and the public set() path so callers cannot bypass the safer helper API. Add regression tests for the advisory payload and for CR, LF, NUL, and bytes values. This preserves existing read behavior for config files that already contain multiline values while preventing GitPython from writing new unsafe values. Co-authored-by: Sebastian Thiel --- git/config.py | 24 ++++++++++++++++++++++-- test/test_config.py | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 55 insertions(+), 2 deletions(-) Index: GitPython-3.1.44/git/config.py =================================================================== --- GitPython-3.1.44.orig/git/config.py +++ GitPython-3.1.44/git/config.py @@ -863,6 +863,24 @@ class GitConfigParser(cp.RawConfigParser return str(value) return force_text(value) + def _value_to_string_safe(self, value: Union[str, bytes, int, float, bool]) -> str: + value_str = self._value_to_string(value) + if re.search(r"[\r\n\x00]", value_str): + raise ValueError("Git config values must not contain CR, LF, or NUL") + return value_str + + @needs_values + @set_dirty_and_flush_changes + def set( + self, + section: str, + option: str, + value: Union[str, bytes, int, float, bool, None] = None, + ) -> None: + if value is not None: + value = self._value_to_string_safe(value) + return super().set(section, option, value) + @needs_values @set_dirty_and_flush_changes def set_value(self, section: str, option: str, value: Union[str, bytes, int, float, bool]) -> "GitConfigParser": @@ -883,9 +901,10 @@ class GitConfigParser(cp.RawConfigParser :return: This instance """ + value_str = self._value_to_string_safe(value) if not self.has_section(section): self.add_section(section) - self.set(section, option, self._value_to_string(value)) + super().set(section, option, value_str) return self @needs_values @@ -910,9 +929,10 @@ class GitConfigParser(cp.RawConfigParser :return: This instance """ + value_str = self._value_to_string_safe(value) if not self.has_section(section): self.add_section(section) - self._sections[section].add(option, self._value_to_string(value)) + self._sections[section].add(option, value_str) return self def rename_section(self, section: str, new_name: str) -> "GitConfigParser": Index: GitPython-3.1.44/test/test_config.py =================================================================== --- GitPython-3.1.44.orig/test/test_config.py +++ GitPython-3.1.44/test/test_config.py @@ -150,6 +150,39 @@ class TestBase(TestCase): git_config = GitConfigParser(config_file) git_config.read() # This should not throw an exception + @with_rw_directory + def test_set_value_rejects_config_injection(self, rw_dir): + config_path = osp.join(rw_dir, "config") + payload = "foo\n[core]\nhooksPath=/tmp/hooks" + + with GitConfigParser(config_path, read_only=False) as git_config: + with pytest.raises(ValueError, match="CR, LF, or NUL"): + git_config.set_value("user", "name", payload) + + with GitConfigParser(config_path, read_only=True) as git_config: + self.assertFalse(git_config.has_section("user")) + self.assertFalse(git_config.has_section("core")) + + @with_rw_directory + def test_set_and_add_value_reject_unsafe_value_characters(self, rw_dir): + config_path = osp.join(rw_dir, "config") + bad_values = ("foo\rbar", "foo\nbar", "foo\x00bar", b"foo\nbar") + + with GitConfigParser(config_path, read_only=False) as git_config: + git_config.add_section("user") + for bad_value in bad_values: + with pytest.raises(ValueError, match="CR, LF, or NUL"): + git_config.set("user", "name", bad_value) + with pytest.raises(ValueError, match="CR, LF, or NUL"): + git_config.set_value("user", "name", bad_value) + with pytest.raises(ValueError, match="CR, LF, or NUL"): + git_config.add_value("user", "name", bad_value) + + git_config.set_value("user", "name", "safe") + + with GitConfigParser(config_path, read_only=True) as git_config: + self.assertEqual(git_config.get_value("user", "name"), "safe") + def test_base(self): path_repo = fixture_path("git_config") path_global = fixture_path("git_config_global")