CVE-2026-11918
Received Received - Intake

IBM ContextForge MCP Gateway Authentication Bypass via Incomplete Payload Inspection

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: IBM Corporation

Description
IBM ContextForge MCP Gateway <= v1.0.4 IBM mcp-context-forge could allow an authenticated user to bypass protection mechanisms due to incomplete recursive inspection of nested payload content.

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Meta Information

Published
2026-09-15
Last Modified
2026-09-15
Generated
2026-09-15
AI Q&A
2026-09-15
EPSS Evaluated
N/A
NVD
CVE-2026-11918
EUVD
EUVD-2026-78898

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
ibm mcp_context_forge to 1.0.4 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-184 The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete.

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Executive Summary

IBM ContextForge MCP Gateway versions up to 1.0.4 have a security filter bypass vulnerability. Authenticated users can bypass configured security controls by nesting malicious payloads one level deeper in the standard MCP tool-call format. The issue occurs because the regex_filter and deny_filter plugins only scan top-level keys in the payload.args structure.

Detection Guidance

To detect this vulnerability, check if your IBM ContextForge MCP Gateway version is 1.0.4 or earlier. Inspect payloads for nested structures in payload.args that bypass top-level filters. Review logs for security filter bypass attempts or unusual nested payloads.

Impact Analysis

An attacker could bypass security protections like PII redaction, secret scrubbing, prompt injection blocking, or forbidden content filtering. This could allow unauthorized access to sensitive data or execution of malicious actions despite security controls being in place.

Compliance Impact

This vulnerability could lead to non-compliance with GDPR or HIPAA by allowing unauthorized access to personal or health data. Security controls designed to protect such data may be bypassed, increasing the risk of data breaches and regulatory penalties.

Mitigation Strategies

Upgrade IBM ContextForge MCP Gateway to version 1.0.5 or later. As a temporary measure, disable the regex_filter and deny_filter plugins to prevent bypass attempts, but note this removes security filtering capabilities.

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