langgraph-api: Relative webhook targets in LangGraph Server can reach in-process routes without authentication
cve-program · CVE-2026-55235
Publishedlanggraph-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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cve-program · CVE-2026-55235
Publishedlanggraph-api: Relative webhook targets in LangGraph Server can reach in-process routes without authentication
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.
- Source published
- 14 Sep 2026 15:53:19 UTC
- Source modified
- 16 Sep 2026 15:14:55 UTC
- Saved here
- 23 Oct 2026 15:48:27 UTC
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CVSS 3.1 · 5.9 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L