CVE-2025-56221
📋 TL;DR
CVE-2025-56221 is an authentication bypass vulnerability in SigningHub v8.6.8 that allows attackers to brute force login credentials due to insufficient rate limiting. This affects all organizations using the vulnerable version of SigningHub for digital signature workflows. Attackers can gain unauthorized access to sensitive document signing systems.
💻 Affected Systems
- SigningHub
📦 What is this software?
Signinghub by Ascertia
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the SigningHub system leading to unauthorized access to all documents, forged digital signatures, and potential data exfiltration of sensitive business documents.
Likely Case
Attackers gain access to user accounts, view sensitive documents, and potentially forge signatures on unauthorized documents.
If Mitigated
With proper rate limiting and monitoring, attacks would be detected and blocked before successful credential compromise.
🎯 Exploit Status
The GitHub reference contains exploit code demonstrating the brute force attack. Attack requires no authentication and uses simple automated tools.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown
Restart Required: No
Instructions:
Check with Ascertia (SigningHub vendor) for security updates. Monitor their security advisories for patch availability.
🔧 Temporary Workarounds
Implement Web Application Firewall (WAF) Rate Limiting
allConfigure WAF rules to limit login attempts per IP address and user account
Enable Account Lockout Policies
allConfigure SigningHub to lock accounts after multiple failed login attempts
🧯 If You Can't Patch
- Implement network-level rate limiting using firewalls or load balancers
- Monitor authentication logs for brute force patterns and implement alerting
🔍 How to Verify
Check if Vulnerable:
Check SigningHub version in admin interface. If version is 8.6.8, system is vulnerable.Check Version:
Check SigningHub admin dashboard or configuration files for version informationVerify Fix Applied:
Test login attempts with automated tools to verify rate limiting is working properly📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts from single IP
- Rapid succession login attempts
- Login attempts with common username patterns
Network Indicators:
- High volume of POST requests to login endpoints
- Traffic patterns showing credential stuffing
SIEM Query:
source="signinghub" AND (event="login_failed" OR event="authentication_failure") | stats count by src_ip, user | where count > 10