CVE-2026-18489: IBM ContextForge MCP Gateway Info Disclosure

CVE-2026-18489 Overview

CVE-2026-18489 is an information disclosure vulnerability in the IBM ContextForge MCP Gateway Translate utility, affecting versions up to and including 1.0.8. The flaw allows a remote unauthenticated attacker to obtain sensitive information belonging to other user sessions. The root cause is exposure of data elements to the wrong session, classified as [CWE-488] Exposure of Data Element to Wrong Session.

Critical Impact
A remote attacker can retrieve sensitive data from concurrent user sessions on the MCP Gateway without authentication, potentially exposing credentials, tokens, and application context data processed through the Model Context Protocol (MCP) translation layer.

Affected Products

IBM ContextForge MCP Gateway Translate utility versions <= 1.0.8
MCP Context Forge deployments using the Translate utility component
Any downstream applications relying on session-isolated MCP context data

Discovery Timeline

2026-09-04 - CVE-2026-18489 published to NVD
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-18489

Vulnerability Analysis

The vulnerability resides in the Translate utility of IBM ContextForge MCP Gateway. The Model Context Protocol (MCP) Gateway brokers context data between AI clients and backend services. The Translate utility processes and transforms MCP messages between sessions.

The utility fails to properly isolate data elements between concurrent sessions. As a result, data intended for one session can be exposed to another session handled by the same gateway instance. An attacker connecting to the gateway can receive data belonging to other users' active sessions.

The vulnerability requires no authentication or user interaction. Exploitation complexity is elevated because the attacker must time requests to coincide with active victim sessions and cannot fully control which session data is returned.

Root Cause

The root cause is improper session scoping within the Translate utility. Data elements processed for one session are stored or dispatched in a context accessible to other sessions. This violates the session isolation principle required for multi-tenant gateway components and matches the [CWE-488] weakness pattern.

Attack Vector

The attack vector is network-based. A remote attacker establishes a session with the MCP Gateway Translate utility and issues requests that cause the utility to return data elements belonging to other active sessions. Because the impact covers both confidentiality and integrity, cross-session data may also be modified in ways that affect victim session state.

No verified proof-of-concept code is publicly available. Refer to the IBM Support Page for vendor technical details.

Detection Methods for CVE-2026-18489

Indicators of Compromise

Unexpected session data appearing in Translate utility responses that does not match the requesting client's session identifier
Anomalous spikes in concurrent session counts against the MCP Gateway endpoint
Log entries showing session IDs referenced across unrelated client IP addresses within short time windows

Detection Strategies

Monitor MCP Gateway application logs for session identifier collisions or reassignment events in the Translate utility
Inspect outbound gateway responses for context data that references user identifiers, tokens, or prompts inconsistent with the requesting session
Correlate network traffic patterns to detect clients receiving response payloads disproportionate to their request volume

Monitoring Recommendations

Enable verbose session-scoped logging on the ContextForge MCP Gateway and forward logs to a centralized SIEM
Baseline normal Translate utility request and response sizes to detect anomalous payloads indicative of cross-session leakage
Alert on repeated connections from single source IPs generating high session churn against the gateway

How to Mitigate CVE-2026-18489

Immediate Actions Required

Identify all deployments of IBM ContextForge MCP Gateway running Translate utility version 1.0.8 or earlier
Apply the vendor-supplied fix referenced on the IBM Support Page
Restrict network access to the MCP Gateway to trusted clients until patching is complete
Rotate any credentials, API tokens, or secrets that may have been transmitted through the affected gateway

Patch Information

IBM has published remediation guidance on the IBM Support Page. Administrators should upgrade beyond version 1.0.8 of the Translate utility component. Verify the deployed version after patching and confirm session isolation behavior in a test environment.

Workarounds

Deploy the MCP Gateway with a single-tenant configuration where each user or application receives an isolated gateway instance
Place the gateway behind an authenticating reverse proxy that terminates and re-establishes sessions per client
Disable the Translate utility if it is not required for production workflows
Enforce strict network segmentation limiting which clients can reach the gateway endpoint

bash

# Configuration example: restrict gateway access at the network layer
iptables -A INPUT -p tcp --dport 4444 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 4444 -j DROP