{"id":"CVE-2021-21423","aliases":["EUVD-2021-0202","GHSA-gg2g-m5wc-vccq","PYSEC-2021-111"],"status":"published","title":"Exposure of Version-Control Repository to an Unauthorized Control Sphere in projen","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.","severity":{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.01392,"percentile":0.72746,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":true},"cwes":["CWE-527"],"published":"2021-04-06T18:35:14Z","modified":"2026-10-20T10:54:30Z","exploits":[{"source":"pocgithub","id":"pvharmo2/gha-lab-b9842b12c0","title":"pvharmo2/gha-lab-b9842b12c0","date":"2026-08-31","url":"https://github.com/pvharmo2/gha-lab-b9842b12c0"}],"fixes":[{"ecosystem":"npm","package":"projen","fixed_in":["0.16.41"],"sources":["ghsa","osv"]},{"ecosystem":"PyPI","package":"projen","fixed_in":["0.16.41"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"projen","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.6.0"},{"fixed":"0.16.41"}]}]},{"source":"ghsa","ecosystem":"PyPI","package":"projen","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.16.41"}]}]},{"source":"osv","ecosystem":"npm","package":"projen","ranges":[{"type":"SEMVER","events":[{"introduced":"0.6.0"},{"fixed":"0.16.41"}]}]},{"source":"osv","ecosystem":"PyPI","package":"projen","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.16.41"}]}],"versions":["0.14.0","0.14.1","0.14.10","0.14.2","0.14.3","0.14.4","0.14.5","0.14.6","0.14.7","0.14.8","0.14.9","0.15.0","0.15.1","0.15.10","0.15.11","0.15.12","0.15.13","0.15.14","0.15.15","0.15.16","0.15.17","0.15.18","0.15.2","0.15.3","0.15.4","0.15.5","0.15.6","0.15.7","0.15.8","0.15.9","0.16.0","0.16.1","0.16.10","0.16.11","0.16.12","0.16.13","0.16.14","0.16.15","0.16.16","0.16.17","0.16.18","0.16.19","0.16.2","0.16.20","0.16.21","0.16.22","0.16.23","0.16.24","0.16.25","0.16.26","0.16.27","0.16.28","0.16.29","0.16.3","0.16.30","0.16.31","0.16.32","0.16.33","0.16.34","0.16.35","0.16.36","0.16.37","0.16.38","0.16.39","0.16.4","0.16.40","0.16.5","0.16.7","0.16.8","0.16.9"]},{"source":"osv","ecosystem":"PyPI","package":"projen","ranges":[{"type":"GIT","events":[{"introduced":"0"},{"fixed":"36030c6a4b1acd0054673322612e7c70e9446643"}]},{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.16.41"}]}],"versions":["0.14.0","0.14.1","0.14.10","0.14.2","0.14.3","0.14.4","0.14.5","0.14.6","0.14.7","0.14.8","0.14.9","0.15.0","0.15.1","0.15.10","0.15.11","0.15.12","0.15.13","0.15.14","0.15.15","0.15.16","0.15.17","0.15.18","0.15.2","0.15.3","0.15.4","0.15.5","0.15.6","0.15.7","0.15.8","0.15.9","0.16.0","0.16.1","0.16.10","0.16.11","0.16.12","0.16.13","0.16.14","0.16.15","0.16.16","0.16.17","0.16.18","0.16.19","0.16.2","0.16.20","0.16.21","0.16.22","0.16.23","0.16.24","0.16.25","0.16.26","0.16.27","0.16.28","0.16.29","0.16.3","0.16.30","0.16.31","0.16.32","0.16.33","0.16.34","0.16.35","0.16.36","0.16.37","0.16.38","0.16.39","0.16.4","0.16.40","0.16.5","0.16.7","0.16.8","0.16.9"]}],"products":[{"vendor":"projen","product":"projen"},{"vendor":"projen_project","product":"projen"}],"references":[{"url":"https://github.com/projen/projen/security/advisories/GHSA-gg2g-m5wc-vccq","tags":["x_refsource_CONFIRM","x_transferred","Mitigation","Third Party Advisory","advisory","web"]},{"url":"https://github.com/projen/projen/commit/36030c6a4b1acd0054673322612e7c70e9446643","tags":["x_refsource_MISC","x_transferred","Patch","Third Party Advisory","fix","web"]},{"url":"https://www.npmjs.com/package/projen","tags":["x_refsource_MISC","x_transferred","Product","Third Party Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21423","tags":["advisory"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/projen/PYSEC-2021-111.yaml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-gg2g-m5wc-vccq"},{"url":"https://github.com/projen/projen","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2021-21423","title":"Exposure of Version-Control Repository to an Unauthorized Control Sphere in projen","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.","status":"published","published":"2021-04-06T18:35:14Z","modified":"2024-08-03T18:09:16.091Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-527"],"updated_at":"2026-11-02T14:33:00.137099Z"}],"euvd":[{"id":"EUVD-2021-0202","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.","status":"published","published":"2021-04-06T18:35:14Z","modified":"2024-08-03T18:09:16Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","level":"medium"}],"updated_at":"2026-11-03T03:25:06.347262Z"}],"ghsa":[{"id":"GHSA-gg2g-m5wc-vccq","title":"Rebuild-bot workflow may allow unauthorised repository modifications","description":"### Impact\n\n`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.\n\nThe 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).\n\nRepositories 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. \n\n### Patches\n\nThe issue was mitigated in version `0.16.41` of the `projen` tool, which removes the `issue_comment` trigger from this workflow. Version `0.17.0` of projen completely removes the `rebuild-bot.yml` workflow.\n\n### Workarounds\n\nThe recommended way to address the vulnerability is to upgrade `projen`. Users who cannot upgrade `projen` may also remove the `.github/workflows/rebuild-bot.yml` file and add it to their `.gitignore` file (via `projenrc.js`) to mitigate the issue.\n\n### References\n\nThe `rebuild-bot.yml` workflow managed by `projen` is only one occurrence of a GitHub Workflows mis-configuration, but it may also be present in other workflows not managed by `projen` (either hand-written, or managed by other tools). For more information on this class of issues, the [Keeping your GitHub Actions and workflows secure: Preventing pwn requests][1] article provides a great overview of the problem.\n \n\n[1]: https://securitylab.github.com/research/github-actions-preventing-pwn-requests","status":"published","published":"2021-04-06T18:36:40Z","modified":"2024-10-21T20:05:49Z","cvss":[{"version":"4.0","score":7.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"},{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","level":"medium"}],"cwes":["CWE-527"],"updated_at":"2026-11-02T14:38:12.325695Z"}],"nvd":[{"id":"CVE-2021-21423","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.","status":"published","published":"2021-04-06T19:15:14.787Z","modified":"2026-06-17T03:35:32.807Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","level":"high","assessor":"primary"},{"version":"2.0","score":5.5,"vector":"AV:N/AC:L/Au:S/C:P/I:P/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-527"],"updated_at":"2026-11-02T14:06:51.610648Z"}],"osv":[{"id":"CVE-2021-21423","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.","status":"published","published":"2021-04-06T19:15:14.787Z","modified":"2026-10-20T10:54:30.282855637Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T15:44:18.004149Z"},{"id":"GHSA-gg2g-m5wc-vccq","title":"Rebuild-bot workflow may allow unauthorised repository modifications","description":"### Impact\n\n`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.\n\nThe 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).\n\nRepositories 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. \n\n### Patches\n\nThe issue was mitigated in version `0.16.41` of the `projen` tool, which removes the `issue_comment` trigger from this workflow. Version `0.17.0` of projen completely removes the `rebuild-bot.yml` workflow.\n\n### Workarounds\n\nThe recommended way to address the vulnerability is to upgrade `projen`. Users who cannot upgrade `projen` may also remove the `.github/workflows/rebuild-bot.yml` file and add it to their `.gitignore` file (via `projenrc.js`) to mitigate the issue.\n\n### References\n\nThe `rebuild-bot.yml` workflow managed by `projen` is only one occurrence of a GitHub Workflows mis-configuration, but it may also be present in other workflows not managed by `projen` (either hand-written, or managed by other tools). For more information on this class of issues, the [Keeping your GitHub Actions and workflows secure: Preventing pwn requests][1] article provides a great overview of the problem.\n \n\n[1]: https://securitylab.github.com/research/github-actions-preventing-pwn-requests","status":"published","published":"2021-04-06T18:36:40Z","modified":"2026-07-08T06:27:36.747299841Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","level":"medium"},{"version":"4.0","score":7.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-527"],"updated_at":"2026-11-02T15:46:47.822182Z"},{"id":"PYSEC-2021-111","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.","status":"published","published":"2021-04-06T19:15:00Z","modified":"2023-11-08T04:04:45.525339Z","updated_at":"2026-11-02T15:52:52.682031Z"}]}}