CVE-2026-8355 IBM ContextForge MCP Gateway is affected by server-side request forgery

What is CVE-2026-8355?

CVE-2026-8355 is a medium-severity server-side request forgery vulnerability in IBM ContextForge MCP Gateway, published on 19 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

IBM ContextForge MCP Gateway 0.1.0 through 1.0.5 is vulnerable to a server-side request Forgery (SSRF) 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.

Weakness: CWE-918

Which versions are affected by CVE-2026-8355?

How do I fix CVE-2026-8355?

No fix has been published for CVE-2026-8355 yet. Limit exposure of the affected software until one is available.

Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.

Is CVE-2026-8355 being exploited?

There is no known exploitation of CVE-2026-8355 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-6f4r-8687-5x9p.