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CVE-2026-8505 – Unauthenticated Webhook Auth Bypass Leading to RCE – IBM Langflow OSS 1.0.0–1.10.0

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Summary

CVE-2026-8505 is a critical authentication bypass vulnerability (CWE-306: Missing Authentication for Critical Function) in IBM Langflow OSS versions 1.0.0 through 1.10.0, carrying a CVSS v3.1 score of 9.8 (Critical). A flaw in the webhook authentication logic allows any unauthenticated remote attacker who knows a flow’s UUID to trigger execution of that flow with owner-level privileges, potentially resulting in Remote Code Execution (RCE). The vulnerability is present in the vast majority of Langflow deployments because the vulnerable condition — WEBHOOK_AUTH_ENABLE set to False — is the default configuration shipped with the product.

Technical details

  • Root cause: The webhook endpoint incorrectly skips API key validation when the WEBHOOK_AUTH_ENABLE configuration option is set to False. Because False is the default value, authentication is disabled on webhook endpoints in standard out-of-the-box installations.
  • Trigger conditions: An attacker needs only network access to the Langflow instance and knowledge of a target flow’s UUID. UUIDs may be discoverable through enumeration or insider knowledge.
  • Attack vector: Network-accessible HTTP/HTTPS webhook endpoint; no authentication, no user interaction, and no prior privileges required (AV:N/AC:L/PR:N/UI:N).
  • Impact: Successful exploitation allows the attacker to execute an arbitrary Langflow AI workflow as its owner. Because Langflow flows can invoke system-level components and external integrations, this provides a pathway to full Remote Code Execution on the underlying server.

Affected software

  • IBM Langflow OSS version 1.0.0 through 1.10.0 (inclusive)

Severity

  • CVSS v3.1 Base Score: 9.8 (Critical)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Mitigation and recommended actions

  • Patch (recommended): Upgrade to Langflow OSS 1.10.1 or later, available on PyPI. This is the vendor-recommended remediation per the IBM Security Bulletin.
  • Configuration mitigation: If an immediate upgrade is not possible, setting WEBHOOK_AUTH_ENABLE=True in the Langflow configuration will enforce API key validation on webhook endpoints and eliminate the bypass condition. Note that this is a configuration-level control, not a formal vendor-acknowledged workaround; patching remains strongly preferred.
  • Network mitigation: Internet-exposed Langflow instances that cannot be patched or reconfigured immediately should be placed behind a network access control or firewall rule restricting inbound access to the webhook endpoint to trusted sources only.

IONIX Status

The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.

References

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