CVE-2025-55000 in OpenBao
Summary
by MITRE • 08/09/2025
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.
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Analysis
by VulDB Data Team • 08/12/2025
The vulnerability identified as CVE-2025-55000 affects OpenBao versions 0.1.0 through 2.3.1 and specifically impacts the TOTP secrets engine functionality. OpenBao is designed as a comprehensive solution for managing sensitive data including secrets, certificates, and cryptographic keys, making it a critical component in enterprise security infrastructure. The TOTP (Time-based One-Time Password) engine serves as a fundamental authentication mechanism within the platform, providing temporary passwords that expire after a short time window to enhance security for access control and multi-factor authentication processes.
The technical flaw stems from improper handling of TOTP code validation within the underlying TOTP library implementation. This vulnerability manifests as a failure to enforce strict one-time use of valid TOTP codes, allowing the same valid code to be accepted multiple times during the authentication process. The root cause lies in unexpected normalization behavior within the TOTP library where the system does not properly validate that a code has already been consumed. This represents a violation of the fundamental security principle that time-based one-time passwords should be consumed exactly once to prevent replay attacks and maintain the integrity of the authentication mechanism. The vulnerability aligns with CWE-308, which addresses the use of a predictable and non-random source of entropy in security functions, and CWE-307, which covers inadequate account lockout mechanisms.
The operational impact of this vulnerability extends beyond simple authentication bypasses and represents a significant security risk for systems relying on OpenBao's TOTP functionality. Attackers could potentially exploit this weakness to repeatedly use the same valid TOTP code for authentication attempts, effectively creating a replay attack vector that undermines the time-sensitive nature of TOTP mechanisms. This vulnerability particularly affects privileged actions within the system since TOTP code verification constitutes a critical security control point. The risk is amplified because the system's design assumes that valid codes should be consumed once and only once, making this behavior a direct violation of established security protocols and authentication best practices. Organizations using OpenBao for sensitive access control may experience unauthorized access if attackers can leverage this multiple acceptance behavior.
Security mitigations for CVE-2025-55000 require immediate implementation of code normalization prior to submission to OpenBao endpoints, as recommended in the advisory. Organizations should ensure that all TOTP codes are first normalized before being processed by the OpenBao system to prevent the underlying library's unexpected behavior from manifesting. System administrators should implement strict monitoring of TOTP code usage patterns to detect potential abuse of this vulnerability. The recommended approach aligns with ATT&CK technique T1566, which covers credential access through the exploitation of weak or predictable authentication mechanisms. Additionally, organizations should consider implementing additional authentication layers or access controls for systems that rely on TOTP verification, ensuring that trusted systems are the sole entities performing code validation. The mitigation strategy should also include regular updates to the OpenBao platform to ensure that patched versions addressing this normalization issue are deployed across all environments.