OpenBao Login MFA Bypass of Rate Limiting and TOTP Token Reuse

Impact

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.

Patches

OpenBao v2.3.2 will patch this issue.

Workarounds

Use of rate-limiting quotas can limit an attacker's ability to exploit this: https://openbao.org/api-docs/system/rate-limit-quotas/

References

This issue was disclosed to HashiCorp and is the OpenBao equivalent of the following tickets:

• https://discuss.hashicorp.com/t/hcsec-2025-19-vault-login-mfa-bypass-of-rate-limiting-and-totp-token-reuse/76038
• https://nvd.nist.gov/vuln/detail/CVE-2025-6015