CVE-2025-55003
📋 TL;DR
OpenBao's MFA system in versions 2.3.1 and below has a TOTP code validation flaw where whitespace in codes bypasses rate limiting, allowing attackers to reuse valid MFA tokens. This affects organizations using OpenBao's TOTP-based MFA for authentication. The vulnerability enables potential unauthorized access to protected secrets and credentials.
💻 Affected Systems
- OpenBao
📦 What is this software?
Openbao by Openbao
⚠️ Risk & Real-World Impact
Worst Case
Attackers bypass MFA entirely, gain unauthorized access to sensitive secrets, certificates, and keys stored in OpenBao, leading to data breaches and privilege escalation.
Likely Case
Targeted attackers bypass rate limiting to perform credential stuffing or brute force attacks against MFA-protected accounts, potentially compromising individual user accounts.
If Mitigated
With proper rate-limiting quotas configured, attack surface is reduced but MFA bypass remains possible through token reuse.
🎯 Exploit Status
Exploitation requires valid user credentials and knowledge of the whitespace bypass technique. No public exploit code is available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.3.2
Vendor Advisory: https://github.com/openbao/openbao/security/advisories/GHSA-rxp7-9q75-vj3p
Restart Required: No
Instructions:
1. Backup OpenBao configuration and data. 2. Download OpenBao 2.3.2 from official repository. 3. Stop OpenBao service. 4. Replace binary with patched version. 5. Restart OpenBao service. 6. Verify functionality.
🔧 Temporary Workarounds
Enable Rate-Limiting Quotas
allConfigure rate-limiting quotas to restrict login attempts and reduce attack surface
bao write sys/quotas/rate-limit/mfa-login rate=10 interval=1s
🧯 If You Can't Patch
- Implement strict rate-limiting quotas on MFA login endpoints
- Monitor authentication logs for unusual patterns of MFA attempts with whitespace characters
🔍 How to Verify
Check if Vulnerable:
Check OpenBao version: if version ≤ 2.3.1 and TOTP MFA is enabled, system is vulnerable.Check Version:
bao versionVerify Fix Applied:
After patching, verify version is 2.3.2 or higher and test that TOTP codes with whitespace are rejected.📡 Detection & Monitoring
Log Indicators:
- Multiple failed MFA attempts from same source
- MFA attempts containing whitespace characters in TOTP codes
- Successful logins after multiple MFA failures
Network Indicators:
- Unusual patterns of authentication requests to MFA endpoints
- High volume of login attempts to protected resources
SIEM Query:
source="openbao" AND (message="*MFA*" OR message="*TOTP*") AND (message="*failed*" OR message="*whitespace*")