External risk intelligence

IBM Langflow OSS Unauthenticated Remote Code Execution via Environment Variable Injection

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-12940

Langflow is a workflow automation and application development platform frequently deployed as a web-based service or API endpoint to facilitate AI and model integration, making it commonly internet-facing or accessible to external users in typical production environments.

OS Command Injection

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory addresses a critical security vulnerability in IBM Langflow OSS affecting versions 1.0.0 through 1.10.1. The issue involves unauthenticated remote code execution, meaning an attacker could potentially run unauthorized commands on affected systems without needing any credentials. This could lead to significant compromise of the affected technology. The primary concern at this stage is to confirm if this specific technology is in use and if it is exposed to potential threats.

Unauthenticated remote code execution risk.
Potentially impacts AI and model integration workflows.
Confirm relevance and exposure to this technology.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by sending specially crafted environment variables to a target system. The MCP stdio launcher in IBM Langflow OSS does not adequately sanitize these variables, allowing malicious input to be executed as code. This can lead to the compromise of the entire system.

Unauthenticated network access required.
Injects environment variables into the launcher.
Enables unauthenticated remote code execution.

Live Threat

Current exploitation, exposure, and threat context

When supported by the advisory, unauthenticated remote code execution could occur via environment variable injection in the MCP stdio launcher. This could affect system operations and data integrity.

System operations and data integrity.
Via network with no authentication.
Unauthorized remote code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

The IBM Langflow OSS vulnerability impacts systems using environment variable injection through the MCP stdio launcher. This issue likely falls under the responsibility of platform or infrastructure teams managing the Langflow deployment, with potential coordination needed from application owners and security teams for remediation. The immediate first step should be to identify all instances of the affected technology, assess their exposure and criticality, and then confirm ownership before planning mitigation.

Platform and application teams own remediation.
Verify affected instances and exposure.
Plan remediation based on business risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is IBM Langflow OSS?

IBM Langflow OSS is a platform designed for building workflow automation and AI applications. It is frequently deployed as a web-based service or API endpoint to help developers integrate various models and data sources into their software.

What does CVE-2026-12940 mean?

This vulnerability is an instance of CWE-78, or OS Command Injection. It occurs because the software fails to properly filter certain dangerous environment variables. An attacker can leverage this weakness to inject malicious instructions that the system executes as if they were legitimate commands.

How can an attacker trigger this vulnerability?

An attacker triggers the bug by sending specially crafted environment variables to the system's MCP stdio launcher. The process fails because the component's blocklist does not account for specific variables like SHELLOPTS, BASHOPTS, or PS4. It is not triggered by standard operations that do not involve interacting with this specific launcher mechanism.

Who should prioritize CVE-2026-12940?

According to Halo Surface Signal, this software is often deployed as an internet-facing service or an accessible API endpoint. Organizations hosting Langflow OSS in environments where it can be reached by external network traffic should consider this a high priority, as the design of the platform makes it a likely target for remote access.

What are the first steps to address this issue?

Begin by creating an inventory of all systems running Langflow OSS versions 1.0.0 through 1.10.1. Once identified, work with your infrastructure and platform teams to confirm which instances are accessible over the network. Assessing the criticality of these deployments will help you coordinate a response plan with application owners.

References

www.ibm.com/support/pages/node/7279995

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.