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Security Bulletin: IBM ContextForge MCP Gateway is affected by server-side request forgery via DNS TOCTOU at tool invocation

Security Bulletin


Summary

IBM ContextForge MCP Gateway (`mcp-contextforge-gateway`) validates REST tool target URLs for server-side request forgery (SSRF) only once, at tool-registration time. When the same tool is later invoked, the stored URL is used directly without re-validation or DNS-resolution pinning, allowing a low-privilege authenticated user to redirect outbound ateway requests to internal network targets by changing the DNS record of an attacker-controlled hostname after registration.

Vulnerability Details

CVEID:   CVE-2026-18905
DESCRIPTION:   MCP Context Forge could allow a remote authenticated attacker to obtain sensitive information due to a DNS rebinding vulnerability during tool invocation.
CWE:   CWE-918: Server-Side Request Forgery (SSRF)
CVSS Source:   IBM
CVSS Base score:   7.7
CVSS Vector:   (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N)

Affected Products and Versions

 

Affected Product(s)Version(s)
IBM ContextForge MCP Gateway (`mcp-contextforge-gateway`)
<= v1.0.6

 

Remediation/Fixes

 

IBM strongly recommends addressing the vulnerability now.

Product(s)Version(s) number and/or range Remediation/Fix/Instructions
IBM ContextForge MCP Gateway<=v1.0.6Upgrade to v1.0.7 or higher. https://github.com/IBM/mcp-context-forge/releases/tag/v1.0.7

 Note:

_Fix merged: 2026-07-29_

  

Workarounds and Mitigations

Workarounds/Mitigation guidance:

No complete workaround exists without upgrading. As a partial mitigation, restrict tool-creation
permissions (`tools.create`) to fully trusted users only, limiting the pool of accounts that could
stage a registration with a controlled hostname. This does not eliminate the vulnerability but
reduces exposure in environments where least-privilege access controls are enforced.

IBM strongly recommends upgrading to v1.0.7 or higher.

Get Notified about Future Security Bulletins

References

Off

Acknowledgement

Change History

02 Sep 2026: Initial Publication

*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.

Disclaimer

According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.

Document Location

Worldwide

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Document Information

Modified date:
02 September 2026

Initial Publish date:
02 September 2026

UID

ibm17286053