CVE-2021-27651: Pega Infinity Auth Bypass Vulnerability

CVE-2021-27651 Overview

CVE-2021-27651 is an authentication bypass vulnerability affecting Pega Infinity versions 8.2.1 through 8.5.2. The vulnerability exists in the password reset functionality for local accounts, which can be exploited to bypass local authentication checks. This flaw allows unauthenticated attackers to gain unauthorized access to the system without valid credentials.

Critical Impact

Unauthenticated attackers can bypass authentication entirely through the password reset mechanism, potentially gaining full access to affected Pega Infinity deployments.

Affected Products

• Pega Infinity versions 8.2.1 through 8.5.2

Discovery Timeline

• 2021-04-29 - CVE-2021-27651 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-27651

Vulnerability Analysis

This vulnerability is classified under CWE-287 (Improper Authentication). The password reset functionality in Pega Infinity contains a logic flaw that fails to properly validate authentication tokens or user identity during the password reset process. An attacker can exploit this weakness to circumvent the normal authentication flow, effectively bypassing local authentication checks without providing valid credentials.

The vulnerability is remotely exploitable without requiring any prior authentication or user interaction, making it particularly dangerous for internet-facing Pega Infinity deployments. The attack complexity is low, meaning exploitation does not require specialized conditions or extensive reconnaissance. Successful exploitation can result in complete compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause lies in improper authentication validation within the password reset workflow. The application fails to adequately verify the authenticity of password reset requests, allowing attackers to manipulate the reset process to gain unauthorized access. This represents a fundamental breakdown in the authentication control mechanism.

Attack Vector

The attack is network-based, requiring only HTTP/HTTPS access to the Pega Infinity web interface. An attacker can target the password reset endpoint and exploit the authentication bypass without any privileges or user interaction. The attack flow typically involves:

1. Accessing the password reset functionality on a target Pega Infinity instance
2. Manipulating the reset request to bypass authentication validation
3. Gaining authenticated access to the application without valid credentials

Due to the sensitive nature of this vulnerability, specific exploitation details are not provided to prevent misuse. Organizations should refer to the Pega Security Advisory A21 Hotfix Matrix for technical details and remediation guidance.

Detection Methods for CVE-2021-27651

Indicators of Compromise

• Unusual password reset requests targeting multiple accounts in rapid succession
• Successful authentication events following password reset requests without legitimate user activity
• Access to administrative functions from unexpected source IP addresses
• Anomalous user account modifications or privilege changes

Detection Strategies

• Monitor web application logs for abnormal patterns in password reset endpoint requests
• Implement alerting for authentication events that follow password reset flows without corresponding user-initiated activity
• Deploy web application firewall (WAF) rules to detect exploitation attempts targeting the password reset functionality
• Correlate authentication logs with password reset activity to identify bypass attempts

Monitoring Recommendations

• Enable detailed logging for all authentication and password reset events in Pega Infinity
• Implement real-time alerting for authentication anomalies detected by SentinelOne Singularity Platform
• Monitor network traffic for suspicious connections to Pega Infinity password reset endpoints
• Review audit logs regularly for signs of unauthorized access following password reset activity

How to Mitigate CVE-2021-27651

Immediate Actions Required

• Apply the appropriate hotfix from Pega immediately for all affected Pega Infinity installations
• Restrict network access to Pega Infinity instances, limiting exposure to trusted networks only
• Review authentication logs for evidence of exploitation attempts or unauthorized access
• Consider disabling local authentication and password reset functionality until patches are applied

Patch Information

Pega has released security hotfixes addressing this vulnerability. Organizations should consult the Pega Security Advisory A21 Hotfix Matrix to identify the appropriate hotfix for their specific Pega Infinity version. The hotfix matrix provides version-specific remediation guidance for versions 8.2.1 through 8.5.2.

Workarounds

• Implement network segmentation to isolate Pega Infinity instances from untrusted networks
• Configure web application firewall rules to block suspicious password reset requests
• Disable local account authentication and enforce SSO/LDAP authentication where possible
• Implement IP allowlisting for administrative access to the Pega Infinity console

# Network-level mitigation example: Restrict access to password reset endpoints
# Configure firewall rules to limit access to trusted IP ranges only
iptables -A INPUT -p tcp --dport 443 -s <trusted_network> -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP