CVE-2026-53708 PUBLISHED

ContextForge: DNS TOCTOU race condition causes SSRF protection bypass (`/admin/gateways/test`)

Assigner: GitHub_M
Reserved: 10.06.2026 Published: 14.09.2026 Updated: 14.09.2026

ContextForge is an AI gateway, registry, and proxy that provides centralized discovery, guardrails, and management for MCP, A2A, and REST or gRPC APIs. Prior to 1.0.3, the /admin/gateways/test call site in mcpgateway/admin.py calls validate_gateway_test_url() in mcpgateway/common/validators.py to resolve and reject private, loopback, link-local, and cloud-metadata addresses, but ResilientHttpClient later resolves the original hostname again without binding the validated address. When MCPGATEWAY_ADMIN_API_ENABLED is enabled, an attacker with a database-backed role containing explicit gateways.read permission can use DNS rebinding to return a public address during validation and a private or metadata address during connection, bypassing ssrf_blocked_networks and ssrf_dns_fail_closed because those controls apply only to the validation-time result. The endpoint's allow_admin_bypass=False setting means a bootstrap-only virtual platform-admin identity without a database role is not sufficient. Successful exploitation can reach internal services and cloud metadata, expose cloud credentials, access internal APIs, or probe internal network ports. This issue is fixed in version 1.0.3.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:N
CVSS Score: 6.6

Product Status

Vendor IBM
Product mcp-context-forge
Versions
  • Version < 1.0.3 is affected
Vendor IBM
Product mcp-contextforge-gateway
Versions
  • Version < 1.0.3 is affected

References

Problem Types

  • CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action CWE
  • CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition CWE
  • CWE-918: Server-Side Request Forgery (SSRF) CWE