Vulnerability Report

CVE-2026-12940

RCE

Title: Unauthenticated RCE via Environment Variable Injection in IBM Langflow OSS

RCE

Proof Of Concept

PoC Available for CVE-2026-12940

CWE Category CWE-78

Published Date Jul 30, 2026

Modified Date Aug 04, 2026

Exploit Status Available

Score 9.8 CVSS v3.1

Exploit Probability (EPSS)

0.48%

Vulnerability Summary

CVE-2026-12940: 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.

Impacted Vendors

langflow 1

Reference Links

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

CVSS v3.1

Source Entity [email protected]

Severity CRITICAL

9.8

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-12940 Exploits & PoCs (Proof Of Concept)

GitHub https://github.com/BiiTts/CVE-2026-12940-Langflow-Unauth-RCE

View Code

August 04, 2026 MODIFIED

Vulnerability data updated via NVD.

July 31, 2026 MODIFIED

Vulnerability data updated via NVD.

July 30, 2026 MODIFIED

Vulnerability data updated via NVD.

July 30, 2026 MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK

Complexity LOW

Privileges N/A

Interaction NONE

CVSS Vector String


                                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Stack

No specific products linked.