CVE-2026-51886 in Langflow
Summary
by MITRE • 10/02/2026
langflow-ai langflow v1.9.3 is affected by: Code Injection. The impact is: execute arbitrary code (remote). The component is: src/backend/base/langflow/api/v1/validate.py:validate-post_validate_code-a-real-authenticated-http-post-to-api-v1. The attack vector is: Attack surface: HTTP or browser-backed service path. A public-facing route accepts raw Python source and forwards it into a server-side compile/exec validation path without any visible entitlement guard. ¶¶ A weakness has been identified in langflow-ai langflow up to 1.9.3. langflow contains a code injection vulnerability in validate-post_validate_code-a-real-authenticated-http-post-to-api-v1 (src/backend/base/langflow/api/v1/validate.py:13). An authenticated attacker can execute arbitrary Python code on the server by submitting malicious code to the /api/v1/validate/code endpoint, which directly executes user-supplied code without sandboxing or security controls.
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Analysis
by VulDB Data Team • 10/02/2026
The vulnerability identified in langflow-ai versions up to 1.9.3 represents a critical server-side code injection flaw located within the API validation module at src/backend/base/langflow/api/v1/validate.py, specifically affecting the post_validate_code endpoint. This component is designed to accept raw Python source code for validation purposes but fails to implement adequate security controls before processing user input. The core technical failure lies in the direct execution of untrusted Python code without any form of sandboxing or restricted environment isolation. When an authenticated user submits a payload via the /api/v1/validate/code endpoint, the backend directly compiles and executes this code within the server's runtime context. This lack of containment allows the attacker to bypass standard application boundaries and interact with the underlying operating system resources as if they were running locally on the host machine.
From an operational perspective, the impact of this vulnerability is severe due to its potential for remote code execution. Although authentication is required to access the endpoint, the absence of entitlement guards or role-based restrictions means that any valid user account can exploit this flaw. The attack vector leverages standard HTTP POST requests, making it accessible through browser-backed services and automated tools alike. Once executed, arbitrary Python commands can lead to complete compromise of the server hosting langflow. This includes the ability to read sensitive configuration files, exfiltrate data stored in associated databases, install backdoors, or pivot further into internal network segments depending on the privileges granted to the application process. The lack of sandboxing ensures that there are no effective barriers preventing destructive actions such as deleting system files or modifying critical application states.
This vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection), specifically reflecting a failure in input validation and secure coding practices regarding dynamic code execution. In the context of the MITRE ATT&CK framework, this behavior maps to T1059 Command and Scripting Interpreter: Python, where an adversary uses native scripting languages to execute commands on a target system. The exploitation path also relates to CWE-78 Improper Neutralization of Special Elements used in an OS Command (OS Command Injection) if the executed code leads to shell interactions, though it is primarily categorized as server-side script injection due to the direct use of Python exec or eval mechanisms without isolation.
Mitigation strategies must prioritize immediate remediation through software updates provided by langflow-ai for versions 1.9.4 and later where this issue has been addressed. In environments where upgrading is not immediately feasible, network-level controls should be implemented to restrict access to the /api/v1/validate/code endpoint exclusively to trusted internal subnets or specific administrative IP ranges using firewall rules or reverse proxy configurations. Additionally, implementing strict input validation that rejects any non-essential characters in code submission fields can reduce the attack surface, although this is not a substitute for proper sandboxing. Application-level mitigations should include enforcing least privilege principles by ensuring the langflow service runs under a restricted user account with minimal system permissions, thereby limiting the potential damage of successful exploitation until a permanent patch is deployed.