CVE-2026-9077 in Langflow OSS
Summary
by MITRE • 08/05/2026
IBM Langflow OSS 1.0.0 through 1.10.3 Langflow allows remote authenticated attackers to bypass localhost-only restrictions and write arbitrary MCP server configurations to IDE configuration files on the host system.
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Analysis
by VulDB Data Team • 08/05/2026
This vulnerability exists in IBM Langflow Open Source Software versions 1.0.0 through 1.10.3, representing a critical security flaw that enables remote authenticated attackers to circumvent localhost-only access controls. The vulnerability stems from insufficient input validation and improper access control mechanisms within the application's configuration handling system. Attackers with valid authentication credentials can exploit this weakness to write arbitrary MCP server configurations directly into IDE configuration files on the host system, effectively allowing them to modify the application's behavior and potentially escalate their privileges.
The technical implementation of this vulnerability involves a flaw in how Langflow processes configuration updates and validates access permissions. When authenticated users submit configuration changes through the application interface, the system fails to properly verify that these modifications originate from authorized sources or that they respect the intended localhost-only restrictions. This creates an opportunity for attackers to inject malicious MCP server configurations that can alter how the application interacts with external services or executes code on the host system. The vulnerability aligns with CWE-284 Access Control Issues, specifically addressing insufficient access control mechanisms that allow unauthorized modification of system resources.
The operational impact of this vulnerability is significant as it provides attackers who have already established authentication credentials with the ability to fundamentally compromise the application's integrity and potentially the entire host system. By writing arbitrary MCP server configurations, attackers can redirect application traffic, inject malicious code, or establish backdoors that persist across application restarts. This type of vulnerability is particularly dangerous in development environments where Langflow might be running with elevated privileges or where configuration changes could affect multiple projects and developers. The attack surface extends beyond simple configuration modification to potentially enable further exploitation through privilege escalation or lateral movement within the network.
From a threat modeling perspective, this vulnerability maps to ATT&CK technique T1059 Command and Scripting Interpreter and T1566 Impair Defenses, as attackers can use the modified configurations to execute unauthorized commands or disable security controls. The weakness essentially allows for a form of configuration-based persistence that could be leveraged by threat actors to maintain access to systems over extended periods. Organizations using IBM Langflow in development environments should consider this vulnerability as potentially enabling more sophisticated attacks including data exfiltration, credential theft, or disruption of development workflows.
Mitigation strategies should include immediate patching of affected versions to the latest available releases that address the access control flaws. Additionally, organizations should implement network segmentation to limit access to Langflow instances and enforce strict access controls on configuration files. Regular security audits of configuration management processes and monitoring for unauthorized configuration changes should be implemented. The principle of least privilege must be enforced by ensuring that user accounts have minimal necessary permissions and that configuration file access is restricted through proper file system permissions. System administrators should also consider implementing automated configuration integrity checking mechanisms to detect unauthorized modifications to critical system files.