langgraph-api implements the LangGraph API for rapid development and testing. Prior to 0.10.0, langgraph-api permits a run or cron to specify a relative webhook target that is delivered through an in-process loopback transport, and the authentication middleware treats that transport as internal without applying the authentication context used for external requests. In deployments that rely on per-user authorization to separate threads and runs, an authenticated user can direct a webhook to the server's own thread and run routes, allowing creation of a run on or modification of another user's thread and limited incorporation of the targeted thread's metadata into the created run record. The affected path requires webhook targets and per-user authorization boundaries; deployments that deliberately re-enable loopback delivery should restrict it to controlled same-process routes because those webhooks remain unauthenticated. This issue is fixed in version 0.10.0.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-2c9q-c2q9-qgqv langgraph-api: Relative webhook targets in LangGraph Server can reach in-process routes without authentication
Fixes

Solution

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Workaround

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History

Mon, 14 Sep 2026 21:00:00 +0000

Type Values Removed Values Added
Description langgraph-api implements the LangGraph API for rapid development and testing. Prior to 0.10.0, langgraph-api permits a run or cron to specify a relative webhook target that is delivered through an in-process loopback transport, and the authentication middleware treats that transport as internal without applying the authentication context used for external requests. In deployments that rely on per-user authorization to separate threads and runs, an authenticated user can direct a webhook to the server's own thread and run routes, allowing creation of a run on or modification of another user's thread and limited incorporation of the targeted thread's metadata into the created run record. The affected path requires webhook targets and per-user authorization boundaries; deployments that deliberately re-enable loopback delivery should restrict it to controlled same-process routes because those webhooks remain unauthenticated. This issue is fixed in version 0.10.0.
Title langgraph-api: Relative webhook targets in LangGraph Server can reach in-process routes without authentication
Weaknesses CWE-287
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-14T15:53:19.013Z

Reserved: 2026-06-16T16:44:00.623Z

Link: CVE-2026-55235

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-14T16:17:12.513

Modified: 2026-09-14T16:17:12.513

Link: CVE-2026-55235

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses