External risk intelligence

IBM Langflow OSS Authentication Bypass Enables Remote Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-8505

The product is designed to handle webhooks, which are typically exposed as public-facing endpoints to receive events from external services. Because the default configuration disables authentication for these endpoints, they are accessible to the public internet by design in common deployments.

Remote Code Execution

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

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in IBM Langflow OSS affects how webhooks are authenticated, potentially allowing unauthorized users to execute any flow. This could lead to the execution of arbitrary code if a flow's unique identifier is known and the system's default security setting is used. The main concern is confirming relevance and exposure.

Unauthenticated access to flow execution.
Default settings enable critical remote code execution.
Verify if your Langflow is exposed externally.

Attack Path

How an attacker could exploit the issue

An attacker can execute any flow in IBM Langflow by exploiting a flaw in its webhook authentication settings. When webhook authentication is disabled, which is the default, an attacker who knows a flow's unique identifier can trigger its execution without needing any credentials. This could lead to the execution of arbitrary code on the system.

Unauthenticated network access is required.
Triggered by knowing a flow's UUID.
Risk of remote code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in IBM Langflow OSS could allow an unauthenticated remote attacker to execute any flow by knowing its UUID, when webhook authentication is disabled. This bypasses API key validation and could lead to unauthorized execution of system actions.

System flows and data could be affected.
Unauthenticated access triggers flow execution.
Potential for unauthorized remote code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in IBM Langflow OSS affects the webhook authentication logic, potentially allowing unauthenticated remote code execution by triggering any flow. Responsibility likely falls to the application owners who manage Langflow instances and their configurations, in coordination with infrastructure or platform teams responsible for the underlying systems. The first practical step is to identify all deployed Langflow instances, determine their internet reachability and business criticality, and confirm the responsible application owner for each instance before planning remediation.

Application owners should manage the issue.
Verify webhook configurations and internet exposure.
Plan remediation based on identified risks.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is IBM Langflow OSS?

IBM Langflow OSS is an open-source tool used to build, manage, and execute data processing flows. It provides a visual interface for connecting components and automation, often used by developers to orchestrate complex tasks or integrate various services through webhooks, which act as endpoints for receiving external data.

What is the authentication bypass in CVE-2026-8505?

This vulnerability is an authentication bypass. It means the software's security checks, which are designed to verify who is allowed to run a task, fail to operate correctly. Specifically, the system skips the required API key validation for webhooks when a specific configuration setting remains at its default value, permitting unauthorized access to trigger flows.

How does an attacker trigger this vulnerability?

An attacker triggers this by sending a request to a flow's specific URL. The primary precondition is knowing the unique identifier (UUID) of the target flow. If the WEBHOOK_AUTH_ENABLE setting is False—the default—the system will execute the flow for anyone who provides that identifier. It does not require an attacker to have a valid user account or existing login credentials.

Why is this considered a high-priority risk?

According to Halo Surface Signal, this is critical because Langflow is designed to process external webhooks, meaning these interfaces are often intentionally exposed to the public internet. Because the default configuration leaves these endpoints unprotected, an internet-facing instance is accessible to anyone online who identifies the flow's UUID.

How do I secure my Langflow instance?

First, identify all deployed Langflow instances in your environment and confirm their current configuration. Check if the webhook authentication setting is enabled; updating this configuration is the primary way to enforce security. Prioritize instances that are reachable from the internet, as these represent the most immediate path for potential unauthorized activity.

References

www.ibm.com/support/pages/node/7278921

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.