ghsa-cwvm-v4w8-q58c
Vulnerability from github
Published
2023-08-30 20:09
Modified
2024-11-19 19:31
Severity ?
4.0 (Medium) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
6.9 (Medium) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Summary
GitPython blind local file inclusion
Details

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.

Show details on source website

To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "GitPython"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.37"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2023-41040"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2023-08-30T20:09:36Z",
    "nvd_published_at": "2023-08-30T22:15:09Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nIn 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\u0027t check if this file is located outside the `.git` directory. This allows an attacker to make GitPython read any file from the system.\n\n### Details\n\nThis vulnerability is present in\n\nhttps://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/refs/symbolic.py#L174-L175\n\nThat code joins the base directory with a user given string without checking if the final path is located outside the base directory.\n\nI was able to exploit it from three places, but there may be more code paths that lead to it:\n\nhttps://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/repo/base.py#L605\n\nhttps://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/repo/base.py#L620\n\nhttps://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/index/base.py#L1353\n\n### PoC\n\nRunning GitPython within any repo should work, here is an example with the GitPython repo.\n\n```python\nimport git\n\nr = git.Repo(\".\")\n\n# This will make GitPython read the README.md file from the root of the repo\nr.commit(\"../README.md\")\nr.tree(\"../README.md\")\nr.index.diff(\"../README.md\")\n\n# Reading /etc/random\n# WARNING: this will probably halt your system, run with caution\n# r.commit(\"../../../../../../../../../dev/random\")\n```\n\n### Impact\n\nI wasn\u0027t able to show the contents of the files (that\u0027s 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).\n\n### Possible solutions\n\nA solution would be to check that the final path isn\u0027t 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.",
  "id": "GHSA-cwvm-v4w8-q58c",
  "modified": "2024-11-19T19:31:26Z",
  "published": "2023-08-30T20:09:36Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-cwvm-v4w8-q58c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-41040"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/pull/1672"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/commit/74e55ee4544867e1bd976b7df5a45869ee397b0b"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/commit/e98f57b81f792f0f5e18d33ee658ae395f9aa3c4"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gitpython-developers/GitPython"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/blob/1c8310d7cae144f74a671cbe17e51f63a830adbf/git/refs/symbolic.py#L174-L175"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/releases/tag/3.1.37"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/gitpython/PYSEC-2023-165.yaml"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2023/09/msg00036.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "GitPython blind local file inclusion"
}


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