Security Bulletin
Summary
IBM ContextForge MCP Gateway contains a server-side request forgery (SSRF) vulnerability in the OAuth gateway registration feature. When a gateway is registered with `auth_type="oauth"` and `grant_type="client_credentials"`, caller-supplied URL fields within `oauth_config` (including `token_url`, `redirect_uri`, and `jwks_uri`) were not uniformly validated against the product's SSRF protection controls, allowing a low-privileged authenticated user with the `gateways.create` permission to cause the gateway to issue outbound HTTP POST requests to internal network addresses — including cloud instance metadata endpoints, loopback services, and RFC 1918 hosts — and to receive a portion of the internal response body echoed back in an HTTP 502 error response.
Vulnerability Details
ID: CVE-2026-8355
DESCRIPTION: A Server-Side Request Forgery (SSRF) vulnerability exists in IBM MCP Context Forge that allows authenticated users with gateway creation privileges to perform arbitrary HTTP POST requests to internal network resources and cloud metadata endpoints. The vulnerability occurs during OAuth-enabled gateway registration when the system fails to validate the oauth_config.token_url parameter.
When registering a gateway with OAuth client credentials authentication, an attacker can supply a malicious token_url pointing to internal services, cloud metadata endpoints (AWS IMDSv1, GCP, Azure), or localhost-bound services. The application immediately performs an HTTP POST request to the attacker-controlled URL with form-encoded credentials in the body. If the response cannot be parsed as a valid OAuth token response, up to 256 characters of the response body are reflected back to the attacker in the HTTP 502 error message.
This vulnerability bypasses existing SSRF protections that are applied to the gateway.url field but not to OAuth configuration parameters.
CWE: CWE-918: Server-Side Request Forgery (SSRF)
CVSS Source: IBM
CVSS Base score: 6.4
CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N))
Affected Products and Versions
| Affected Product(s) | Version(s) |
|
IBM ContextForge MCP Gateway
| <=v1.0.5 |
Remediation/Fixes
IBM strongly recommends addressing the vulnerability now.
| Product(s) | Version(s) number and/or range | Remediation/Fix/Instructions |
|
IBM ContextForge MCP Gateway
| 2.0>=v1.0.6 |
Upgrade to v1.0.6 or later. See release notes: https://github.com/IBM/mcp-context-forge/releases/tag/v1.0.6
|
Workarounds and Mitigations
Get Notified about Future Security Bulletins
References
Acknowledgement
Change History
31 Aug 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:
31 August 2026
Initial Publish date:
31 August 2026
UID
ibm17285723