Ghost: Blind Password Hash Disclosure in Ghost Admin API

Impact

Any staff-level user was able to leak the hashed passwords of other staff users. An offline password-guessing attack against the hashes could lead to account takeover if successful, but Device Verification should have prevented an attacker from logging in with a recovered password. Depending on the database used, leaked hashes may not have had the correct casing for all characters, increasing the difficulty of a password-guessing attack.

Vulnerable versions

This vulnerability is present in Ghost versions v6.54.0 and earlier.

Patches

v6.54.1 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, ensure all staff users have Multi-factor Authentication (MFA) enabled. This will help prevent an attacker from logging in with any passwords that are successfully recovered from the leaked hashes.

References

Ghost thanks Chapman Schleiss for disclosing this vulnerability responsibly.

For more information

If you have any questions or comments about this advisory, email us at security@ghost.org.