IBM Langflow up to 1.10.1 MCP stdio launcher util.py injection

Summaryinfo

A vulnerability classified as critical has been found in IBM Langflow up to 1.10.1. This affects an unknown part of the file src/lfx/src/lfx/base/mcp/util.py of the component MCP stdio launcher. This manipulation causes injection. The identification of this vulnerability is CVE-2026-12940. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical was found in IBM Langflow up to 1.10.1. Affected by this vulnerability is some unknown processing of the file src/lfx/src/lfx/base/mcp/util.py of the component MCP stdio launcher. The manipulation with an unknown input leads to a injection vulnerability. The CWE definition for the vulnerability is CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at ibm.com. This vulnerability is known as CVE-2026-12940 since 06/22/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 07/30/2026). The attack technique deployed by this issue is T1055 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-51240). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• IBM

Name

• Langflow

Version

• 1.10.0
• 1.10.1

License

• commercial

Website

• Vendor: https://www.ibm.com/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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