CVE-2020-26222.yml

---
gem: dependabot-common
cve: 2020-26222
ghsa: 23f7-99jx-m54r
url: https://github.com/dependabot/dependabot-core/security/advisories/GHSA-23f7-99jx-m54r
date: 2020-11-13
title: Remote code execution in dependabot-core branch names when cloning
description: |
  ### Impact
  Remote code execution vulnerability in `dependabot-common` and
  `dependabot-go_modules` when a source branch name contains malicious
  injectable bash code.

  For example, if Dependabot is configured to use the following source branch
  name: `"/$({curl,127.0.0.1})"`, Dependabot will make a HTTP request to the
  following URL: 127.0.0.1 when cloning the source repository.

  When Dependabot is configured to clone the source repository during an update,
  Dependabot runs a shell command to git clone the repository:

  ```bash
  git clone --no-tags --no-recurse-submodules --depth=1 --branch=<BRANCH> --single-branch <GITHUB_REPO_URL> repo/contents/path
  ```

  Dependabot will always clone the source repository for `go_modules` during the
  file fetching step and can be configured to clone the repository for other
  package managers using the `FileFetcher` class from `dependabot-common`.

  ```ruby
  source = Dependabot::Source.new(
    provider: "github",
    repo: "repo/name",
    directory: "/",
    branch: "/$({curl,127.0.0.1})",
  )

  repo_contents_path = "./file/path"
  fetcher = Dependabot::FileFetchers.for_package_manager("bundler").
                    new(source: source, credentials: [],
                    repo_contents_path: repo_contents_path)
  fetcher.clone_repo_contents
  ```

  ### Workarounds
  Escape the branch name prior to passing it to the `Dependabot::Source` class.

  For example using `shellwords`:

  ```ruby
  require "shellwords"
  branch = Shellwords.escape("/$({curl,127.0.0.1})")
  source = Dependabot::Source.new(
    provider: "github",
    repo: "repo/name",
    directory: "/",
    branch: branch,
  )
  ```
cvss_v3: 8.7
patched_versions:
  - ">= 0.125.1"

unaffected_versions:
  - "< 0.119.0.beta1"

related:
  url:
    - https://github.com/dependabot/dependabot-core/pull/2727