OpenBao exists to provide a software solution to manage, store, and distribute sensitive data including secrets, certificates, and keys. In versions 0.1.0 through 2.3.1, when using OpenBao's userpass auth method, user enumeration was possible due to timing difference between non-existent users and users with stored credentials. This is independent of whether the supplied credentials were valid for the given user.

This issue was fixed in version 2.3.2. To work around this issue, users may use another auth method or apply rate limiting quotas to limit the number of requests in a period of time: https://openbao.org/api-docs/system/rate-limit-quotas/.