CVE-2026-12940

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Unauthenticated RCE via Environment Variable Injection in IBM Langflow OSS

Publication date: 2026-07-30

Last updated on: 2026-07-30

Assigner: IBM Corporation

Description

IBM Langflow OSS 1.0.0 through 1.10.1 are vulnerable to unauthenticated remote code execution via environment variable injection in the MCP (Model Context Protocol) stdio launcher. The vulnerability exists in src/lfx/src/lfx/base/mcp/util.py where the DANGEROUS_ENV_VARS blocklist fails to include SHELLOPTS , BASHOPTS , and PS4 environment variables.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-07-30

Last Modified

2026-07-30

Generated

2026-07-31

AI Q&A

2026-07-31

EPSS Evaluated

N/A

NVD

CVE-2026-12940

EUVD

EUVD-2026-51240

Affected Vendors & Products

Vendor	Product	Version / Range
ibm	langflow	From 1.0.0 (inc) to 1.10.1 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-78	The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Attack-Flow Graph

Executive Summary

IBM Langflow OSS versions 1.0.0 through 1.10.1 are vulnerable to unauthenticated remote code execution due to environment variable injection in the MCP stdio launcher. The issue occurs in src/lfx/src/lfx/base/mcp/util.py where the blocklist for dangerous environment variables fails to include SHELLOPTS, BASHOPTS, and PS4.

Detection Guidance

Check for unauthorized environment variable modifications, especially SHELLOPTS, BASHOPTS, or PS4. Inspect logs for unusual MCP stdio launcher activity or unexpected remote commands.

Impact Analysis

An attacker could exploit this to execute arbitrary code remotely without authentication. This could lead to full system compromise, data theft, or unauthorized access to sensitive information.

Compliance Impact

This vulnerability could lead to unauthorized access and data breaches, violating GDPR and HIPAA requirements for data protection and access controls. Non-compliance may result in legal penalties and reputational damage.

Mitigation Strategies

Upgrade IBM Langflow OSS to a version beyond 1.10.1. Remove dangerous environment variables from MCP stdio launcher configurations. Restrict network access to MCP endpoints.

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