TechDocs Mkdocs Configuration Key Enables Arbitrary Code Execution
Date: 2026-03
Affected: npm/@backstage/plugin-techdocs-node
Attack vector: rce
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-29186
CWE: CWE-434
CWE-74
CVSS: 7.7 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L)

### 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.or


Mitigations:

Architectural layers (MAESTRO):