GHSA-wjw6-2cqr-j4qr

### Impact In both clients (`tuf/client` and `tuf/ngclient`), there is a path traversal vulnerability that in the worst case can overwrite files ending in `.json` anywhere on the client system on a call to `get_one_valid_targetinfo()`. It occurs because the rolename is used to form the filename, and may contain path traversal characters (ie `../../name.json`). The impact is mitigated by a few facts: * It only affects implementations that allow arbitrary rolename selection for delegated targets metadata * The attack requires the ability to A) insert new metadata for the path-traversing role and B) get the role delegated by an existing targets metadata * The written file content is heavily restricted since it needs to be a valid, signed targets file. The file extension is always .json. ### Patches A fix is available in version 0.19 or newer. ### Workarounds None that do not require code changes. Clients can restrict the allowed character set for rolenames, or they can store metadata in files named in a way that is not vulnerable: neither of these approaches is possible without modifying python-tuf. ### References - [The issue where this was discovered](https://github.com/theupdateframework/python-tuf/issues/1527) - [Proof of Concept demonstrating the flaw](https://github.com/jku/path-traversal-poc) ### For more information If you have any questions or comments about this advisory: * Open an issue in [python-tuf](https://github.com/theupdateframework/python-tuf/issues) * Contact the maintainers by email or Slack