Backstage is an open framework for building developer portals. Prior to 1.14.6, the @backstage/plugin-techdocs-node package is affected by improper validation of mkdocs theme configuration in techdocs. When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in mkdocs.yml that cause arbitrary code execution during the documentation build process. This issue is fixed in versions 1.14.6 and 1.15.4.

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

### Impact

When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in `mkdocs.yml` that cause arbitrary code execution during the documentation build process.

### Patches

Patched in `@backstage/plugin-techdocs-node` version `1.15.4`

### Workarounds

- Configure TechDocs with `techdocs.generator.runIn: 'docker'` instead of `'local'` to provide container isolation, though this does not fully mitigate the risk. - Restrict write access to repositories registered in the Backstage catalog to trusted users.