CVE-2026-77822 in ContextForge MCP Gateway
Summary
by MITRE • 09/04/2026
IBM ContextForge MCP Gateway could allow a remote authenticated attacker to obtain sensitive information due to server-side request forgery via DNS rebinding.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in IBM ContextForge MCP Gateway represents a critical security flaw rooted in the implementation of Server-Side Request Forgery mechanisms, specifically exacerbated by DNS rebinding techniques. This issue allows an authenticated attacker to bypass internal network restrictions and access sensitive resources that are typically isolated from external or untrusted networks. The core technical failure lies in how the gateway processes incoming requests and validates their origins. When a user with valid credentials interacts with the application, the server may process subsequent requests without adequately verifying whether those requests originate from trusted local interfaces or if they have been manipulated through DNS manipulation techniques that trick the server into believing a malicious external request is coming from an internal source.
DNS rebinding operates by exploiting the time gap between DNS resolution and actual connection establishment. An attacker controls a domain name associated with their own infrastructure but configures it to resolve initially to a public IP address, allowing them to authenticate against the IBM ContextForge MCP Gateway using valid credentials. Once authenticated, the attacker modifies the DNS record for that same domain to point to an internal private IP address, such as those used by management interfaces of other network devices or sensitive backend services within the corporate environment. Because many web applications and gateways rely solely on the hostname provided in the HTTP Host header or perform insufficient validation against the actual resolved IP address during subsequent requests, the server accepts these rebinding attacks as legitimate internal traffic. This effectively neutralizes security controls that depend on source IP filtering or network segmentation boundaries.
The operational impact of this vulnerability is severe, particularly for organizations relying on IBM ContextForge MCP Gateway to manage and orchestrate multi-cloud environments. By leveraging DNS rebinding combined with SSRF, an attacker can probe the internal network topology, access administrative consoles of routers, switches, firewalls, or other critical infrastructure components that are not exposed directly to the internet but are reachable from the gateway's host machine. This leads to unauthorized disclosure of sensitive configuration data, credentials stored in accessible files, and potentially allows for further lateral movement within the enterprise network. The ability to interact with internal services means an attacker could disrupt operations by modifying configurations or exfiltrate proprietary information that was never intended to be accessed via a web-facing application interface.
This vulnerability aligns closely with CWE-918, which describes Server-Side Request Forgery (SSRF) flaws where the server retrieves resources from user-supplied URLs without proper validation of the destination's trustworthiness or network location. Furthermore, it maps to MITRE ATT&CK technique T1557, specifically Adversary-in-the-Middle and DNS Rebinding variants like T1048 which involves Exfiltration Over Alternative Protocol mechanisms often used in conjunction with SSRF for data theft. The lack of strict IP address validation after DNS resolution is a common oversight that undermines the principle of least privilege by granting web applications implicit trust over internal network segments they should not be able to reach directly from untrusted sources.
Mitigation strategies must focus on rigorous input validation and network-level controls rather than relying solely on application logic. Organizations should implement strict allow-listing for any URLs or IP addresses that the IBM ContextForge MCP Gateway is permitted to access, ensuring that only explicitly trusted internal endpoints are reachable. It is crucial to validate not just the hostname but also resolve it dynamically at request time and compare the resulting IP address against a list of allowed private ranges if such access is intended, while blocking known RFC 1918 addresses unless specifically required for legitimate business functions. Additionally, deploying network segmentation measures that isolate the gateway from sensitive internal management networks can reduce the blast radius even if an SSRF vulnerability exists. Regular security assessments and penetration testing focused on DNS rebinding scenarios are recommended to identify similar weaknesses in other web-facing applications within the infrastructure.