CVE-2026-101061 in python-utcp
Summary
by MITRE • 09/27/2026
utcp-gql before 1.1.1 and utcp-websocket before 1.1.1 contain server-side request forgery vulnerabilities due to incomplete application of CVE-2026-44661 fixes. The GraphQL plugin uses a vulnerable prefix check allowing bypass URLs like http://127.0.0.1.attacker.example, while the WebSocket plugin performs no URL validation despite documented security requirements. Attackers can force connections to internal services and cloud metadata endpoints by supplying malicious tool URLs in call templates, and receive configured API keys and OAuth tokens sent to attacker-controlled hosts.
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Analysis
by VulDB Data Team • 09/27/2026
The vulnerability identified in utcp-gql versions prior to 1.1.1 and utcp-websocket versions prior to 1.1.1 represents a critical server-side request forgery flaw resulting from the incomplete remediation of CVE-2026-44661. This issue stems from fundamental failures in input validation logic within both the GraphQL plugin and the WebSocket plugin, allowing attackers to manipulate outbound network connections initiated by the application. The core technical deficiency lies in how these components handle user-supplied URLs embedded within call templates or configuration parameters intended for external tool integration. Instead of enforcing strict allow-lists or robust sanitization routines, the applications rely on insufficient checks that can be trivially bypassed using standard evasion techniques common to SSRF attacks.
In the GraphQL plugin specifically, the vulnerability is driven by a flawed prefix validation mechanism designed to restrict requests to safe domains while blocking access to internal network ranges. However, this check fails to account for domain suffix injection or DNS rebinding variations that effectively neutralize simple string matching algorithms. By supplying URLs such as http://127.0.0.1.attacker.example, an attacker can exploit the way certain HTTP clients and underlying libraries resolve hostnames. The application may interpret the subdomain portion as part of a permitted external domain while the actual connection target resolves to localhost or other internal IP addresses due to local DNS configuration overrides or misconfigured resolvers. This allows the server to make requests to services that are otherwise inaccessible from the public internet, effectively bypassing perimeter security controls and network segmentation strategies intended to isolate backend infrastructure.
The WebSocket plugin exhibits an even more severe deficiency by performing no URL validation whatsoever despite documented security requirements mandating such safeguards. When a user provides a malicious tool URL within a call template, the application blindly forwards requests to that destination without verifying whether it points to internal resources, cloud metadata endpoints, or other sensitive services. This lack of restriction enables attackers to force the server to interact with arbitrary hosts under their control or target critical internal infrastructure such as database servers, administrative interfaces, and configuration management systems. The absence of any validation logic means there is no barrier preventing the exploitation of this flaw through simple parameter manipulation in WebSocket messages or associated GraphQL mutations that trigger these outbound connections.
The operational impact of these vulnerabilities extends beyond mere network reconnaissance to significant data exfiltration risks. Attackers can leverage SSRF capabilities to access cloud metadata endpoints, which often contain temporary credentials, IAM roles, and other sensitive authentication material necessary for accessing cloud resources. Furthermore, because the vulnerability involves forcing the server to send requests that may include configured API keys or OAuth tokens, attackers can intercept these credentials if they control the destination host of the forged request. This leads directly to credential theft and potential compromise of downstream services authenticated via those tokens. The ability to receive sensitive data sent to attacker-controlled hosts transforms a network-level flaw into a severe confidentiality breach with implications for identity management and access control across the entire environment.
From an industry standard perspective, this vulnerability aligns closely with CWE-918 Server-Side Request Forgery (SSRF), specifically reflecting weaknesses in input validation and URL parsing logic. The exploitation technique of using subdomain injection to bypass domain checks is a classic SSRF pattern often associated with improper neutralization of special elements used in web requests. Additionally, the ability to access internal services maps directly to ATT&CK T1598 Phishing for Inbound Credentials when considering the interception aspect, and more broadly to T1046 Network Service Discovery if used for mapping internal assets. The failure to validate URLs against a strict allow-list also indicates non-compliance with secure coding practices outlined in OWASP guidelines regarding server-side request forgery prevention.
Mitigation strategies must prioritize immediate patching of both utcp-gql and utcp-websocket components to version 1.1.1 or later, where the fixes for CVE-2026-44661 are fully implemented with robust validation logic. Until patches can be applied, organizations should implement network-level controls such as egress filtering rules that restrict outbound connections from application servers to only known and necessary external domains. Internal services requiring protection should not listen on public interfaces or use firewall rules to block traffic originating from the compromised server's IP address. Additionally, deploying web application firewalls with SSRF detection capabilities can provide a layer of defense by identifying anomalous request patterns targeting internal IP ranges or cloud metadata endpoints. It is also critical to audit existing call templates and WebSocket configurations for any pre-existing malicious entries that may have been injected during previous exploitation attempts.