CVE-2021-21423: `projen` is a project generation tool that synthesizes project configuration files such as `package.json`, `tsconfig.json`, `.gitignore`, GitHub Workf...

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.

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS Probability

1.38%

68.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-527

Affected Software

Vendor	Product	Versions
Projen Project	Projen	>= 0.6.0, < 0.16.41

References

https://github.com/projen/projen/commit/36030c6a4b1acd0054673322612e7c70e9446643Patch, Third Party Advisory
https://github.com/projen/projen/security/advisories/GHSA-gg2g-m5wc-vccqMitigation, Third Party Advisory
https://www.npmjs.com/package/projenProduct, Third Party Advisory
https://github.com/projen/projen/commit/36030c6a4b1acd0054673322612e7c70e9446643Patch, Third Party Advisory
https://github.com/projen/projen/security/advisories/GHSA-gg2g-m5wc-vccqMitigation, Third Party Advisory
https://www.npmjs.com/package/projenProduct, Third Party Advisory

Timeline

Published: Apr 6, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21423?

`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.

How severe is CVE-2021-21423?

CVE-2021-21423 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 1.38% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21423?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.