GHSA-jx35-x7fj-vgpr Ghost Content API filter bypass reveals private fields

• npm ghost: >= 5.46.1, < 6.21.2 → fixed in 6.21.2

Impact The validation applied to filters on the public API endpoints could be partially bypassed, making it possible to reveal private fields via a brute force attack. If SQLite was used as the database password hashes were fully accessible. If MySQL was used as the database the password hashes' case (uppercase / lowercase) would have been lost, which would likely have rendered a further brute force attack on the discovered hashes fruitless. Vulnerable versions This vulnerability is present in Ghost from v5.46.1 up to v6.21.1. Patches v6.21.2 contains a fix for this issue. How to update For self-hosters using Docker, find Docker's official Ghost image here. Updating a Docker-based Ghost instance is documented here. If your Ghost is a Ghost-CLI install see our documentation on updating it to the latest version here. Workarounds If upgrading immediately is not possible, block or filter requests to Content API endpoints where the `filter` query parameter contains `password` or `email` (including any compound form such as `users.password`, `users.email`, `authors.password`, `authors.email`). Reject requests at a reverse proxy / WAF layer before they reach Ghost. Example (case-insensitive) pattern to block on the raw querystring: ``` filter=[^&]*(password|email) ``` References Ghost thanks crnkovic for disclosing this vulnerability responsibly. For more information If you have any questions or comments about this advisory, email Ghost at [email protected].