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, OpenBao's TOTP secrets engine could accept valid codes multiple times rather than strictly-once. This was caused by unexpected normalization in the underlying TOTP library. To work around, ensure that all codes are first normalized before submitting to the OpenBao endpoint. TOTP code verification is a privileged action; only trusted systems should be verifying codes.