An information disclosure vulnerability was identified in GitHub Enterprise Server that allowed private repositories to be added to a GitHub Actions runner group via the API by a user who did not have access to those repositories, resulting in the repository names being shown in the UI. To exploit this vulnerability, an attacker would need access to the GHES instance, permissions to modify GitHub Actions runner groups, and successfully guess the obfuscated ID of private repositories. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.7 and was fixed in versions 3.3.17, 3.4.12, 3.5.9, 3.6.5. This vulnerability was reported via the GitHub Bug Bounty program.

A code injection vulnerability was identified in GitHub Enterprise Server that allowed setting arbitrary environment variables from a single environment variable value in GitHub Actions when using a Windows based runner. To exploit this vulnerability, an attacker would need existing permission to control the value of environment variables for use with GitHub Actions. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.8.0 and was fixed in versions 3.4.15, 3.5.12, 3.6.8, 3.7.5. This vulnerability was reported via the GitHub Bug Bounty program.

GitHub Actions Runner is the application that runs a job from a GitHub Actions workflow. The actions runner invokes the docker cli directly in order to run job containers, service containers, or container actions. A bug in the logic for how the environment is encoded into these docker commands was discovered in versions prior to 2.296.2, 2.293.1, 2.289.4, 2.285.2, and 2.283.4 that allows an input to escape the environment variable and modify that docker command invocation directly. Jobs that use container actions, job containers, or service containers alongside untrusted user inputs in environment variables may be vulnerable. The Actions Runner has been patched, both on `github.com` and hotfixes for GHES and GHAE customers in versions 2.296.2, 2.293.1, 2.289.4, 2.285.2, and 2.283.4. GHES and GHAE customers may want to patch their instance in order to have their runners automatically upgrade to these new runner versions. As a workaround, users may consider removing any container actions, job containers, or service containers from their jobs until they are able to upgrade their runner versions.

Github's CodeQL action is provided to run CodeQL-based code scanning on non-GitHub CI/CD systems and requires a GitHub access token to connect to a GitHub repository. The runner and its documentation previously suggested passing the GitHub token as a command-line parameter to the process instead of reading it from a file, standard input, or an environment variable. This approach made the token visible to other processes on the same machine, for example in the output of the `ps` command. If the CI system publicly exposes the output of `ps`, for example by logging the output, then the GitHub access token can be exposed beyond the scope intended. Users of the CodeQL runner on 3rd-party systems, who are passing a GitHub token via the `--github-auth` flag, are affected. This applies to both GitHub.com and GitHub Enterprise users. Users of the CodeQL Action on GitHub Actions are not affected. The `--github-auth` flag is now considered insecure and deprecated. The undocumented `--external-repository-token` flag has been removed. To securely provide a GitHub access token to the CodeQL runner, users should **do one of the following instead**: Use the `--github-auth-stdin` flag and pass the token on the command line via standard input OR set the `GITHUB_TOKEN` environment variable to contain the token, then call the command without passing in the token. The old flag remains present for backwards compatibility with existing workflows. If the user tries to specify an access token using the `--github-auth` flag, there is a deprecation warning printed to the terminal that directs the user to one of the above options. All CodeQL runner releases codeql-bundle-20210304 onwards contain the patches. We recommend updating to a recent version of the CodeQL runner, storing a token in your CI system's secret storage mechanism, and passing the token to the CodeQL runner using `--github-auth-stdin` or the `GITHUB_TOKEN` environment variable. If still using the old flag, ensure that process output, such as from `ps`, is not persisted in CI logs.