Path traversal for local publishers in TechDocs backend
### Impact
A malicious actor with the ability to register entities in the Software Catalog is able to write files to arbitrary paths on the techdocs backend host instance when `techdocs.publisher.type` is set to `local`.
This vulnerability is mitigated by the fact that the Software Catalog must be configured with non-standard field format validators and/or non-standard entity policies.
### Patches
Those affected are advised to upgrade to `@backstage/plugin-techdocs-node` version `1.1.2` or higher.
### Workarounds
If patching or upgrading is not possible, it would be sufficient to update any custom Catalog field format validators and/or cus
Backstage is an open platform for building developer portals, and techdocs-common contains common functionalities for Backstage's TechDocs. In `@backstage/techdocs-common` versions prior to 0.6.3, a malicious actor could read sensitive files from the environment where TechDocs documentation is built and published by setting a particular path for `docs_dir` in `mkdocs.yml`. These files would then be available over the TechDocs backend API. This vulnerability is mitigated by the fact that an attacker would need access to modify the `mkdocs.yml` in the documentation source code, and would also need access to the TechDocs backend API. The vulnera
Backstage is an open platform for building developer portals, and techdocs-common contains common functionalities for Backstage's TechDocs. In versions of `@backstage/tehdocs-common` prior to 0.6.4, a malicious internal actor is able to upload documentation content with malicious scripts. These scripts would normally be sanitized by the TechDocs frontend, but by tricking a user to visit the content via the TechDocs API, the content sanitazion will be bypassed. If the TechDocs API is hosted on the same origin as the Backstage app or other backend plugins, this may give access to sensitive data. The ability to upload malicious content may be li