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Security Bulletin: IBM ContextForge MCP Gateway is affected by server-side request forgery (DNS rebinding) via the A2A agent invocation endpoint

Security Bulletin


Summary

IBM ContextForge MCP Gateway contains a server-side request forgery (SSRF) vulnerability in its Agent-to-Agent (A2A) invocation endpoint (POST /a2a/{agent_name}/invoke). Unlike every other outbound egress path in the gateway, the A2A invocation path does not pin the DNS-resolved IP address at connection time, allowing an authenticated low-privileged user to bypass the gateway's SSRF protections through a classic DNS-rebinding attack and cause the gateway to issue outbound HTTP requests to internal network resources, with the full response body returned to the caller.

Vulnerability Details

CVEID:   CVE-2026-77822
DESCRIPTION:   MCP Context Forge could allow a remote authenticated attacker to obtain sensitive information due to server-side request forgery via DNS rebinding.
CWE:   CWE-918: Server-Side Request Forgery (SSRF)
CVSS Source:   IBM
CVSS Base score:   8.2
CVSS Vector:   (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N)

Affected Products and Versions

 

Affected Product(s)Version(s)
IBM ContextForge MCP Gateway
<= v1.0.8

 

Remediation/Fixes

 

IBM strongly recommends addressing the vulnerability now.

Product(s)Version(s) number and/or range Remediation/Fix/Instructions
IBM ContextForge MCP Gateway<= v1.0.8Upgrade to v1.0.9 

 Note: <Component A / B names> are bundled with <Product profile name> to provide <feature / function description>

  

Workarounds and Mitigations

Operators who cannot immediately upgrade can reduce exposure by:

1. **Disable A2A** — set the environment variable `MCPGATEWAY_A2A_ENABLED=False` to disable the A2A subsystem entirely. This removes the vulnerable endpoint from the attack surface at the cost of A2A functionality.
2. **Restrict A2A create/invoke permissions** — revoke A2A creation and invocation rights from developer and team_admin roles in environments where A2A is not required.
3. **Network-level egress controls** — enforce outbound network policy at the host or cloud level to block the gateway process from reaching cloud metadata endpoints and private RFC 1918 address ranges, preventing exploitation of the DNS-rebinding window even if a rebind attempt succeeds.

None of these mitigations eliminate the underlying vulnerability; IBM strongly recommends upgrading to the fixed version.

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References

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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

ibm17286055