External risk intelligence

Langflow Unauthenticated Server Space Exhaustion and Path Disclosure Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-55450

Langflow is an application platform for deploying AI agents and workflows. As a development and deployment tool for web-based agents and APIs, it is commonly exposed as a web-accessible service or management interface, making it likely to be reachable from the internet in typical deployment scenarios.

Information Disclosure

Langflow

before 1.9.1

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory concerns a critical vulnerability in Langflow, a tool used for building AI agents and workflows. The issue allows unauthenticated users to upload excessive data, potentially exhausting server resources and revealing file paths, which could aid in further attacks. The primary concern is to confirm if this technology is in use and assess potential exposure.

Unrestricted file uploads can exhaust server space.
Confirms if this AI tool is present in our environment.
Assess if this AI platform is exposed externally.

Attack Path

How an attacker could exploit the issue

An attacker with network access to Langflow can upload any amount of data to the server without authentication, potentially causing space exhaustion. The server also reveals the absolute path of the uploaded file, which could aid attackers in chaining further actions.

No prior authentication needed.
Uploading arbitrary data.
Space exhaustion and information leak.

Live Threat

Current exploitation, exposure, and threat context

Unauthenticated users with network access to Langflow could exploit this vulnerability to exhaust server storage by uploading arbitrary amounts of data. When supported by the advisory, the system may also leak the absolute path of uploaded files, potentially aiding attackers in chaining further actions.

Server storage exhaustion.
Upload any amount of data.
Service disruption.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability affects Langflow deployments and could lead to server space exhaustion and information leakage. The primary responsibility for addressing this typically lies with the teams managing the Langflow application and its underlying infrastructure, such as platform or application owners. The immediate first step should be to identify all Langflow instances, assess their exposure and criticality, confirm the responsible owner, and then plan remediation activities.

Application or platform teams should own remediation.
Verify server reachability and resource utilization.
Plan and execute the vendor-provided fix.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is Langflow and what is it used for?

Langflow is a specialized software platform designed for building, testing, and deploying AI-powered agents and automated workflows. It provides a visual interface for developers to connect various components, such as language models and data tools, making it a central hub for managing AI-driven application logic and infrastructure.

What does CVE-2026-55450 mean for Langflow security?

This CVE highlights two main weaknesses: uncontrolled resource consumption and sensitive information exposure. Specifically, it involves an Uncontrolled Resource Consumption vulnerability (CWE-400) allowing storage exhaustion, and an Exposure of Sensitive Information (CWE-200) where the system reveals internal file paths to unauthenticated users.

How can an attacker trigger this vulnerability?

An attacker can trigger this by sending unauthorized file upload requests directly to the Langflow server. This process does not require any prior authentication or special credentials. Simply having network connectivity to the application is sufficient to initiate these uploads; this bug is not triggered by standard, legitimate administrative use of the platform.

Is my Langflow instance at risk?

According to Halo Surface Signal, Langflow is frequently deployed as a web-accessible service or management interface. If your instance is reachable from the internet, it is considered externally exposed and therefore more accessible to unauthorized users compared to instances restricted to internal, private networks.

What should I do to address this vulnerability?

The first step is to identify all running instances of Langflow within your environment and determine who manages them. Once located, verify if your version is prior to 1.9.1. If so, coordinate with your application or platform teams to plan and apply the vendor-provided fix, which resolves these security gaps.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.