CVE-2026-42867 Langflow: Path Traversal in Knowledge Bases API via Creation Endpoint

What is CVE-2026-42867?

CVE-2026-42867 is a medium-severity path traversal vulnerability in Langflow Langflow, published on 23 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.0, Langflow is vulnerable to Path Traversal in the Knowledge Bases API (POST /api/v1/knowledge_bases). This occurs because user-supplied knowledge base names are used directly to create file paths without proper sanitization or containment checks. An authenticated attacker can exploit this flaw to create directories and write files anywhere on the server's filesystem. This vulnerability is fixed in 1.9.0.

Weakness: CWE-22

Which versions are affected by CVE-2026-42867?

3 open source packages ship an affected version, including langflow. It affects 1 product.

Products include Langflow Langflow.

How do I fix CVE-2026-42867?

Upgrade langflow to 1.9.0 or later.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2026-42867 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42867 exists.

Other vulnerabilities in Langflow Langflow

• CVE-2026-9198 IBM Langflow Code Injection Exploited Critical 9.8
• CVE-2026-0770 Langflow Inclusion of Functionality from Untrusted Control Sphere Exploited Critical 9.8
• CVE-2025-3248 Langflow Missing Authentication Exploited Critical 9.8
• CVE-2025-34291 Langflow Origin Validation Error Exploited Critical 9.4
• CVE-2026-33017 Langflow Code Injection Exploited Critical 9.3

All Langflow Langflow vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-79ph-745m-6wxq, PYSEC-2026-2566.