CVE-2020-37094: EspoCRM Authentication Bypass Vulnerability

CVE-2020-37094 Overview

CVE-2020-37094 is an authentication bypass vulnerability affecting EspoCRM version 5.8.5. This flaw allows attackers to access other user accounts by manipulating authorization headers. By decoding and modifying Basic Authorization and Espo-Authorization tokens, attackers can gain unauthorized access to administrative user information and privileges, potentially compromising the entire CRM system.

Critical Impact

Attackers can escalate privileges to administrative accounts by manipulating authorization tokens, leading to full compromise of sensitive customer relationship data and system configurations.

Affected Products

• EspoCRM 5.8.5

Discovery Timeline

• 2026-02-03 - CVE CVE-2020-37094 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2020-37094

Vulnerability Analysis

This vulnerability is classified under CWE-639 (Authorization Bypass Through User-Controlled Key), which occurs when an application uses user-controlled data to access authorization resources without properly validating that the user has permission to access the specified resource.

In EspoCRM 5.8.5, the authentication mechanism improperly handles authorization headers, allowing authenticated users to manipulate the Basic Authorization and Espo-Authorization tokens. The application fails to adequately verify that the decoded token values correspond to the authenticated user's session, enabling horizontal and vertical privilege escalation attacks.

The network-accessible nature of this vulnerability means that any authenticated user with low privileges can potentially access administrative accounts without requiring any user interaction from the target.

Root Cause

The root cause of this vulnerability lies in the improper validation of authorization tokens within EspoCRM's authentication handling code. When processing authentication requests, the application decodes the authorization headers but fails to properly validate that the user identity contained within the token matches the authenticated session. This insecure direct object reference allows attackers to substitute their own user identifiers with those of other users, including administrators.

Attack Vector

The attack exploits the network-accessible authentication endpoints in EspoCRM. An attacker with valid low-privilege credentials can:

1. Capture their own authorization header during a legitimate authentication request
2. Decode the Base64-encoded Basic Authorization or Espo-Authorization token
3. Modify the user identifier within the decoded token to target another user account
4. Re-encode the modified token and submit it in subsequent requests
5. Gain access to the targeted user's account, including administrative accounts

The vulnerability requires low privileges (valid user credentials) but no user interaction, making it particularly dangerous in multi-tenant CRM environments where users may have varying privilege levels.

Detection Methods for CVE-2020-37094

Indicators of Compromise

• Unusual authentication patterns where a single source IP authenticates as multiple different users in rapid succession
• Authorization header manipulation attempts visible in web server access logs showing modified or malformed tokens
• Unexpected administrative actions performed by accounts that typically have limited privileges
• Audit log entries showing access to sensitive records by users who should not have visibility

Detection Strategies

• Monitor authentication logs for users accessing accounts other than their own established session patterns
• Implement anomaly detection for authorization header values that deviate from expected token structures
• Review access logs for privilege escalation attempts, particularly access to administrative endpoints from non-admin accounts
• Deploy web application firewalls (WAF) with rules to detect Base64-encoded token manipulation attempts

Monitoring Recommendations

• Enable detailed logging for all authentication and authorization events in EspoCRM
• Implement real-time alerting for failed authentication attempts followed by successful admin-level access
• Regularly audit user access patterns to identify anomalous behavior indicative of account takeover
• Monitor for multiple concurrent sessions originating from the same user but with different privilege levels

How to Mitigate CVE-2020-37094

Immediate Actions Required

• Upgrade EspoCRM to a patched version that addresses the authorization bypass vulnerability
• Implement additional authentication controls such as IP-based session binding
• Review audit logs for evidence of exploitation and identify potentially compromised accounts
• Reset credentials for all administrative accounts as a precautionary measure

Patch Information

Organizations running EspoCRM 5.8.5 should immediately check for available security updates from the EspoCRM Official Website. Additional technical details about this vulnerability can be found in the Exploit-DB #48376 entry and the VulnCheck Security Advisory.

Workarounds

• Implement network-level access controls to restrict CRM access to trusted networks only
• Deploy a reverse proxy with additional authentication layers to validate user sessions independently
• Disable or restrict API access if not required for business operations
• Implement strict session management with server-side validation of all authorization tokens
• Consider temporary disabling of external access until patches can be applied