CriticalVulnerability

CVE-2026-12940: IBM Langflow OSS unauthenticated code execution via MCP stdio launcher

Source: NVD(opens in a new tab)
Identifier: CVE-2026-12940
Published: July 30, 2026
Record updated: October 9, 2026

Known exploitation: Not listed in the CISA Known Exploited Vulnerabilities catalog at the last check.
EPSS: 0.9%

Summary

CVE-2026-12940 affects IBM Langflow OSS versions 1.0.0 through 1.10.1. The flaw is in the MCP (Model Context Protocol) stdio launcher, in src/lfx/src/lfx/base/mcp/util.py, where the DANGEROUS_ENV_VARS blocklist omits SHELLOPTS, BASHOPTS, and PS4. Per the source, this allows unauthenticated remote code execution through environment variable injection and is classified as CWE-78, OS Command Injection. NVD had not yet provided an assessment at publication on 07/30/2026.

Mitigation

The source does not state a fix yet. Check the original advisory for updates.

Details

Scores and exploitation

CVSS score: 9.8(critical)
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector: network
Attack complexity: low
Privileges required: none
User interaction: none
EPSS: 0.9%Estimated probability that this CVE is exploited in the next 30 days, from the FIRST Exploit Prediction Scoring System. Read on November 4, 2026.
Disclosure date: July 30, 2026

Weaknesses and techniques

Weakness (CWE): CWE-78
Attack pattern (CAPEC): CAPEC-88

Classification

Attack type: Other
Attack sophistication: Trivial
AI component targeted: Framework
Impact: Confidentiality,
Integrity,
Availability
Labels: security

How this record was produced

Summaries, mitigations and labels on this page are generated automatically from the source. The linked source is authoritative. The source gives this advisory a description and no title, so the title above is a headline generated from the source text.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-12940

First tracked: July 30, 2026 at 02:08 PM ET, from NVD/CVE Database

Classifier: claude-haiku-5-5, prompt v4

Classifier confidence: 95% (self-assessed)

Topics

Model Context Protocol

Summary

Mitigation

Topics

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