CVE-2023-41040: GitPython blind local file inclusion
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.
python import git
r = git.Repo(".")
This will make GitPython read the README.md file from the root of the repo r.commit("../README.md") r.tree("../README.md") r.index.diff("../README.md")
Reading /etc/random WARNING: this will probably halt your system, run with caution r.commit("../../../../../../../../../dev/random")
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.
Other sources
GitPython is a python library used to interact with Git repositories. 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. 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. This vulnerability cannot be used to read the contents of files but could in theory be used to trigger a denial of service for the program. This issue has been addressed in version 3.1.37.
— NVD
GitPython is a python library used to interact with Git repositories. 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. 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. This vulnerability cannot be used to read the contents of files but could in theory be used to trigger a denial of service for the program. This issue has not yet been addressed.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2023-41040?
CVE-2023-41040 has been classified with a medium severity level due to the potential for directory traversal vulnerabilities.
How do I fix CVE-2023-41040?
To fix CVE-2023-41040, upgrade GitPython to version 3.1.37 or later.
Which versions of GitPython are affected by CVE-2023-41040?
GitPython versions up to and including 3.1.34 are affected by CVE-2023-41040.
What are the potential impacts of CVE-2023-41040?
The primary impact of CVE-2023-41040 is the risk of unauthorized file access through directory traversal.
Is CVE-2023-41040 specific to any platforms or distributions?
CVE-2023-41040 affects GitPython across multiple platforms, but specific fixes may be provided by distributions like Red Hat.