# CVE-2026-55235: langgraph-api: Relative webhook targets in LangGraph Server can reach in-process routes without authentication

> CVE-2026-55235: langgraph-api: Relative webhook targets in LangGraph Server can reach in-process routes without authentication. CVSS 5.9 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-55235
Last updated: 2026-09-30T17:51:56Z

- Published: 2026-09-14 15:53 UTC · Updated: 2026-09-30 17:51 UTC · Assigner: GitHub\_M
- CVSS: 5.9 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L
- EPSS: 0.37%, 30th percentile (scored 2026-11-05)
- CISA KEV: no
- CWE: CWE-287

## 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.

## Affected vendors and products

- langchain-ai: langgraph-api

## Tracked companies

- [LangChain (LangSmith)](https://rewindex.com/company/langchain-langsmith.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-55235)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-55235)
- [https://github.com/langchain-ai/docs/blob/7b70fbacab21f84d9c6f9848f86cdeb471adbb50/src/langsmith/agent-server-changelog.mdx](https://github.com/langchain-ai/docs/blob/7b70fbacab21f84d9c6f9848f86cdeb471adbb50/src/langsmith/agent-server-changelog.mdx)
- [https://github.com/langchain-ai/helm/security/advisories/GHSA-2c9q-c2q9-qgqv](https://github.com/langchain-ai/helm/security/advisories/GHSA-2c9q-c2q9-qgqv)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-55235 · Markdown: https://rewindex.com/cve/CVE-2026-55235.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-55235 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-11-05T18:42:24.167Z