CVE-2026-105741 in Langflow
Summary
by MITRE • 10/05/2026
Langflow is a tool for building and deploying AI-powered agents and workflows. From 1.5.0 until 1.10.3, an IP spoofing vulnerability in the Model Context Protocol (MCP) configuration installation endpoint (POST /api/v1/mcp/project/{project_id}/install) allowed authenticated remote attackers to bypass the "local-only" access restriction. By sending a spoofed X-Forwarded-For: 127.0.0.1 header, an attacker could make the server treat the request as originating from localhost, letting them write/overwrite an MCP client configuration file on the server's filesystem. This vulnerability is fixed in 1.10.3.
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Analysis
by VulDB Data Team • 10/05/2026
Langflow serves as a comprehensive platform for constructing and deploying artificial intelligence agents and automated workflows, facilitating complex interactions between large language models and external tools or data sources. Within this ecosystem, the Model Context Protocol (MCP) plays a critical role in defining how these AI components communicate with local resources and services. The security integrity of such configurations is paramount, as misconfigurations can lead to unauthorized access to sensitive system files or unintended execution of arbitrary code through injected tool definitions.
A significant vulnerability was identified in Langflow versions ranging from 1.5.0 up to 1.10.3 concerning the installation endpoint for MCP project configurations. Specifically, the POST /api/v1/mcp/project/{project_id}/install route contained a logic flaw related to access control validation. The application implemented a security measure intended to restrict certain configuration changes to local-only operations, presumably to prevent remote attackers from modifying critical system settings via network requests. However, this restriction relied entirely on trusting the X-Forwarded-For HTTP header without proper sanitization or verification of the actual source IP address.
This design flaw allows authenticated remote attackers to perform an IP spoofing attack by manipulating the X-Forwarded-For header. By setting this header to 127.0.0.1, which represents localhost in IPv4 addressing schemes, the attacker can deceive the server into believing that the request originates from a trusted local source. Consequently, the application bypasses its internal checks designed to block remote modifications, effectively treating an external network request as if it were generated locally on the machine hosting Langflow.
The operational impact of this vulnerability is severe due to the nature of MCP configurations. Once the access restriction is bypassed, an attacker can write or overwrite MCP client configuration files directly onto the server's filesystem. These configuration files often dictate how AI agents interact with external tools, databases, and APIs. Maliciously crafted configurations could enable remote code execution, data exfiltration, or the establishment of persistent backdoors within the AI workflow pipeline. This represents a critical escalation from simple authentication bypass to potential full system compromise depending on the privileges under which Langflow operates.
From a classification perspective, this vulnerability aligns with CWE-287 Improper Authentication and CWE-915 Improper Modification of Objects with Multiple References. The failure to validate the true origin of the request against trusted proxies or internal network boundaries is characteristic of insecure direct object reference patterns where trust assumptions are incorrectly applied to HTTP headers commonly used in load-balanced environments. In terms of attack vectors, this falls under ATT&CK technique T1078 Valid Accounts and potentially T1562 Impair Defenses if the modified configurations disable logging or security monitoring features within the AI agent framework.
Mitigation strategies primarily involve upgrading to Langflow version 1.10.3 or later, where this logic flaw has been corrected by implementing robust source IP verification mechanisms that do not rely solely on spoofable headers. For environments unable to upgrade immediately, administrators should ensure that reverse proxies such as Nginx or Apache are configured to overwrite the X-Forwarded-For header with the actual client IP address rather than appending to it, thereby preventing clients from injecting arbitrary values. Additionally, restricting access to the API endpoints via network-level controls like firewalls can provide an additional layer of defense against remote exploitation attempts targeting this specific endpoint.