OpenBao Login MFA Bypasses Rate Limiting and TOTP Token Reuse

Vulnerability Description

OpenBao exists to provide a software solution to manage, store, and distribute sensitive data including secrets, certificates, and keys. In versions 2.3.1 and below, OpenBao's Login Multi-Factor Authentication (MFA) system allows enforcing MFA using Time-based One Time Password (TOTP). Due to normalization applied by the underlying TOTP library, codes were accepted which could contain whitespace; this whitespace could bypass internal rate limiting of the MFA method and allow reuse of existing MFA codes. This issue was fixed in version 2.3.2. To work around this, use of rate-limiting quotas can limit an attacker's ability to exploit this: https://openbao.org/api-docs/system/rate-limit-quotas/.

References

• https://github.com/openbao/openbao/security/advisories/GHSA-rxp7-9q75-vj3p
• https://github.com/openbao/openbao/commit/8340a6918f6c41d8f75b6c3845c376d9dc32ed19
• https://discuss.hashicorp.com/t/hcsec-2025-19-vault-login-mfa-bypass-of-rate-limiting-and-totp-token-reuse/76038