CVE-2025-36115: IBM Sterling B2B Auth Bypass Vulnerability

CVE-2025-36115 Overview

IBM Sterling Connect:Express Adapter for Sterling B2B Integrator versions 5.2.0.00 through 5.2.0.12 contains a session fixation vulnerability (CWE-384). The application does not properly invalidate session identifiers after use, which could allow an authenticated user to impersonate another user on the system. This session management flaw enables attackers with valid credentials to hijack or reuse session tokens, potentially gaining unauthorized access to other users' data and functionality.

Critical Impact

Authenticated attackers can exploit improper session invalidation to impersonate other users, potentially accessing sensitive business data and performing unauthorized actions within the B2B integration platform.

Affected Products

• IBM Sterling Connect:Express Adapter for Sterling B2B Integrator 5.2.0.00
• IBM Sterling Connect:Express Adapter for Sterling B2B Integrator versions through 5.2.0.12
• IBM Sterling B2B Integrator environments utilizing the affected adapter versions

Discovery Timeline

• 2026-01-20 - CVE CVE-2025-36115 published to NVD
• 2026-01-20 - Last updated in NVD database

Technical Details for CVE-2025-36115

Vulnerability Analysis

This vulnerability is classified as Session Fixation (CWE-384), a session management weakness where the application fails to properly invalidate or regenerate session identifiers. In the context of IBM Sterling Connect:Express Adapter, the application does not disallow session IDs after use, meaning that once a session token is established, it remains valid even after it should have been terminated or replaced.

The impact of this vulnerability allows an authenticated user to potentially impersonate another user on the system. This could lead to unauthorized access to sensitive B2B transaction data, manipulation of integration workflows, or disclosure of confidential business information processed through the Sterling B2B Integrator platform.

Root Cause

The root cause lies in improper session lifecycle management within the IBM Sterling Connect:Express Adapter. The application fails to implement proper session invalidation mechanisms, allowing session tokens to remain active beyond their intended lifespan. This violates the principle of session management security, which requires that session identifiers be invalidated upon logout, privilege level changes, or timeout events.

Attack Vector

An attacker must first obtain valid authentication credentials to the system. Once authenticated, the attacker can exploit the session fixation vulnerability through the following general approach:

1. The attacker authenticates to the IBM Sterling Connect:Express Adapter and obtains a valid session ID
2. Due to improper session invalidation, the session token may persist or be reusable
3. The attacker can potentially use knowledge of session token patterns or capture another user's session ID through network interception
4. With the captured or predicted session ID, the attacker can impersonate the victim user
5. The attacker gains access to the victim's data and can perform actions under their identity

The vulnerability requires network access and low privileges to exploit initially, but successful exploitation can impact confidentiality, integrity, and availability of data belonging to other users on the system.

Detection Methods for CVE-2025-36115

Indicators of Compromise

• Multiple concurrent sessions from the same session ID originating from different IP addresses
• Unusual login patterns where a user appears active from geographically disparate locations simultaneously
• Session tokens being reused after explicit logout events in application logs
• Anomalous access to resources by users who should not have permission based on their normal access patterns

Detection Strategies

• Implement session monitoring to detect reuse of session identifiers across different client contexts
• Review authentication and session management logs for signs of session token reuse or fixation attempts
• Monitor for authentication anomalies where user behavior changes dramatically mid-session
• Deploy SentinelOne Singularity XDR to detect suspicious authentication patterns and potential impersonation attacks

Monitoring Recommendations

• Enable detailed logging for all authentication and session management events in Sterling B2B Integrator
• Configure alerts for session anomalies such as session ID reuse after logout
• Implement continuous monitoring of user activity patterns to detect potential impersonation
• Review access logs regularly for unauthorized data access or privilege abuse

How to Mitigate CVE-2025-36115

Immediate Actions Required

• Review the IBM Support Page for official patch information and guidance
• Audit current session management configurations in your Sterling B2B Integrator deployment
• Implement additional session validation controls at the network or application gateway level
• Review user access logs to identify any potential past exploitation of this vulnerability

Patch Information

IBM has published security guidance for this vulnerability. Organizations running IBM Sterling Connect:Express Adapter for Sterling B2B Integrator versions 5.2.0.00 through 5.2.0.12 should consult the IBM Support Page for official patch availability and installation instructions. Apply the appropriate security update as soon as it becomes available to address the session fixation vulnerability.

Workarounds

• Implement network segmentation to limit exposure of the affected adapter to only trusted networks
• Enable additional authentication factors (MFA) to reduce the impact of session impersonation
• Configure shorter session timeout values to reduce the window of opportunity for session reuse attacks
• Consider implementing web application firewall (WAF) rules to detect and block suspicious session behavior
• Monitor and restrict access to the Sterling B2B Integrator administrative interfaces

Organizations should prioritize applying the official IBM security patch when available. For detailed configuration guidance and temporary mitigations, refer to the IBM Support Page.