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This PR contains the following updates:
==3.1.34
->==3.1.41
GitHub Vulnerability Alerts
CVE-2023-41040
Summary
In order to resolve some git references, GitPython reads files from the
.git
directory, in some places the name of the file being read is provided by the user, GitPython doesn't check if this file is located outside the.git
directory. This allows an attacker to make GitPython read any file from the system.Details
This vulnerability is present in
https://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/refs/symbolic.py#L174-L175
That code joins the base directory with a user given string without checking if the final path is located outside the base directory.
I was able to exploit it from three places, but there may be more code paths that lead to it:
https://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/repo/base.py#L605
https://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/repo/base.py#L620
https://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/index/base.py#L1353
PoC
Running GitPython within any repo should work, here is an example with the GitPython repo.
Impact
I wasn't able to show the contents of the files (that's why "blind" local file inclusion), depending on how GitPython is being used, this can be used by an attacker for something inoffensive as checking if a file exits, or cause a DoS by making GitPython read a big/infinite file (like
/dev/random
on Linux systems).Possible solutions
A solution would be to check that the final path isn't located outside the
repodir
path (maybe even after resolving symlinks). Maybe there could be other checks in place to make sure that the reference names are valid.CVE-2024-22190
Summary
This issue exists because of an incomplete fix for CVE-2023-40590. On Windows, GitPython uses an untrusted search path if it uses a shell to run
git
, as well as when it runsbash.exe
to interpret hooks. If either of those features are used on Windows, a maliciousgit.exe
orbash.exe
may be run from an untrusted repository.Details
Although GitPython often avoids executing programs found in an untrusted search path since 3.1.33, two situations remain where this still occurs. Either can allow arbitrary code execution under some circumstances.
When a shell is used
GitPython can be told to run
git
commands through a shell rather than as direct subprocesses, by passingshell=True
to any method that accepts it, or by both settingGit.USE_SHELL = True
and not passingshell=False
. Then the Windowscmd.exe
shell process performs the path search, ad GitPython does not prevent that shell from finding and runninggit
in the current directory.When GitPython runs
git
directly rather than through a shell, the GitPython process performs the path search, and currently omits the current directory by settingNoDefaultCurrentDirectoryInExePath
in its own environment during thePopen
call. Although thecmd.exe
shell will honor this environment variable when present, GitPython does not not currently pass it into the shell subprocess's environment.Furthermore, because GitPython sets the subprocess CWD to the root of a repository's working tree, using a shell will run a malicious
git.exe
in an untrusted repository even if GitPython itself is run from a trusted location.This also applies if
Git.execute
is called directly withshell=True
(or afterGit.USE_SHELL = True
) to run any command.When hook scripts are run
On Windows, GitPython uses
bash.exe
to run hooks that appear to be scripts. However, unlike when running git, no steps are taken to avoid finding and runningbash.exe
in the current directory.This allows the author of an untrusted fork or branch to cause a malicious
bash.exe
to be run in some otherwise safe workflows. An example of such a scenario is if the user installs a trusted hook while on a trusted branch, then switches to an untrusted feature branch (possibly from a fork) to review proposed changes. If the untrusted feature branch contains a maliciousbash.exe
and the user's current working directory is the working tree, and the user performs an action that runs the hook, then although the hook itself is uncorrupted, it runs with the maliciousbash.exe
.Note that, while
bash.exe
is a shell, this is a separate scenario from whengit
is run using the unrelated Windowscmd.exe
shell.PoC
On Windows, create a
git.exe
file in a repository. Then create aRepo
object, and call any method through it (directly or indirectly) that supports theshell
keyword argument withshell=True
:The
git.exe
executable in the repository directory will be run.Or use no
Repo
object, but do it from the location with thegit.exe
:The
git.exe
executable in the current directory will be run.For the scenario with hooks, install a hook in a repository, create a
bash.exe
file in the current directory, and perform an operation that causes GitPython to attempt to run the hook:The
bash.exe
executable in the current directory will be run.Impact
The greatest impact is probably in applications that set
Git.USE_SHELL = True
for historical reasons. (Undesired console windows had, in the past, been created in some kinds of applications, when it was not used.) Such an application may be vulnerable to arbitrary code execution from a malicious repository, even with no other exacerbating conditions. This is to say that, if a shell is used to rungit
, the full effect of CVE-2023-40590 is still present. Furthermore, as noted above, running the application itself from a trusted directory is not a sufficient mitigation.An application that does not direct GitPython to use a shell to run
git
subprocesses thus avoids most of the risk. However, there is no such straightforward way to prevent GitPython from runningbash.exe
to interpret hooks. So while the conditions needed for that to be exploited are more involved, it may be harder to mitigate decisively prior to patching.Possible solutions
A straightforward approach would be to address each bug directly:
NoDefaultCurrentDirectoryInExePath
into the subprocess environment, when a shell is used, since then the subprocess is thecmd.exe
shell that actually performs the path search.NoDefaultCurrentDirectoryInExePath
in the GitPython process environment during thePopen
call made to run hooks with abash.exe
subprocess.These need only be done on Windows.
Release Notes
gitpython-developers/GitPython (GitPython)
### [`v3.1.41`](https://togithub.com/gitpython-developers/GitPython/releases/tag/3.1.41): - fix Windows security issue [Compare Source](https://togithub.com/gitpython-developers/GitPython/compare/3.1.40...3.1.41) The details about the Windows security issue [can be found in this advisory](https://togithub.com/gitpython-developers/GitPython/security/advisories/GHSA-2mqj-m65w-jghx). Special thanks go to [@EliahKagan](https://togithub.com/EliahKagan) who reported the issue and fixed it in a single stroke, while being responsible for an incredible amount of improvements that he contributed over the last couple of months ❤️. #### What's Changed - Add `__all__` in git.exc by [@EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1719](https://togithub.com/gitpython-developers/GitPython/pull/1719) - Set submodule update cadence to weekly by [@EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1721](https://togithub.com/gitpython-developers/GitPython/pull/1721) - Never modify sys.path by [@EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1720](https://togithub.com/gitpython-developers/GitPython/pull/1720) - Bump git/ext/gitdb from `8ec2390` to `ec58b7e` by [@dependabot](https://togithub.com/dependabot) in [https://github.com/gitpython-developers/GitPython/pull/1722](https://togithub.com/gitpython-developers/GitPython/pull/1722) - Revise comments, docstrings, some messages, and a bit of code by [@EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1725](https://togithub.com/gitpython-developers/GitPython/pull/1725) - Use zero-argument super() by [@EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1726](https://togithub.com/gitpython-developers/GitPython/pull/1726) - Remove obsolete note in \_iter_packed_refs by [@EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1727](https://togithub.com/gitpython-developers/GitPython/pull/1727) - Reorganize test_util and make xfail marks precise by [@EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1729](https://togithub.com/gitpython-developers/GitPython/pull/1729) - Clarify license and make module top comments more consistent by [@EliahKagan](https://togithub.com/EliahKagan) in [https://github.com/gitpython-developers/GitPython/pull/1730](https://togithub.com/gitpython-developers/GitPython/pull/1730) - Deprecate compat.is\_Configuration
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