Backstage is an open framework for building developer portals. Prior to version 1.14.3, this is a configuration bypass vulnerability that enables arbitrary code execution. The @backstage/plugin-techdocs-node package uses an allowlist to filter dangerous MkDocs configuration keys during the documentation build process. A gap in this allowlist allows attackers to craft an mkdocs.yml that causes arbitrary Python code execution, completely bypassing TechDocs' security controls. This issue has been patched in version 1.14.3.

Affected: npm: @backstage/plugin-techdocs-node

### Impact This is a configuration bypass vulnerability that enables arbitrary code execution. The `@backstage/plugin-techdocs-node` package uses an allowlist to filter dangerous MkDocs configuration keys during the documentation build process.

A gap in this allowlist allows attackers to craft an `mkdocs.yml` that causes arbitrary Python code execution, completely bypassing TechDocs' security controls.

### Patches

Patched in `@backstage/plugin-techdocs-node` version 1.14.3

### Workarounds If users cannot upgrade immediately:

1. Use Docker mode with restricted access: Configure TechDocs with `runIn: docker` instead of `runIn: local`. This provides container isolation, though it does not fully mitigate the risk. 2. Restrict repository access: Limit who can modify `mkdocs.yml` files in repositories that TechDocs processes. Only allow trusted contributors. 3. Manual review: Implement PR review requirements for changes to `mkdocs.yml` files to detect malicious hooks configurations before they are merged. 4. Downgrade MkDocs: Use MkDocs < 1.4.0 (e.g., 1.3.1) which does not support hooks. Note: This may limit access to newer MkDocs features.

Note: Building documentation in CI/CD pipelines using `@techdocs/cli` does not mitigate this vulnerability, as the CLI uses the same vulnerable `@backstage/plugin-techdocs-node` package.

### Resources [MkDocs Hooks Documentation](https://www.mkdocs.org/user-guide/configuration/#hooks) [MkDocs 1.4 Release Notes](https://www.mkdocs.o…

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