---
id: CVE-2026-55235
title: langgraph-api implements the LangGraph API for rapid development and testing
summary: >-
  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 a…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L'
cwe:
  - CWE-287
vendor: langgraph-api
product: langgraph-api
affected:
  - langgraph-api < 0.10.0
patched:
  - langgraph-api 0.10.0
published: '2026-09-14'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T16:17:09.373'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55235'
references:
  - url: >-
      https://github.com/langchain-ai/docs/blob/7b70fbacab21f84d9c6f9848f86cdeb471adbb50/src/langsmith/agent-server-changelog.mdx
    label: security-advisories@github.com
  - url: >-
      https://github.com/langchain-ai/helm/security/advisories/GHSA-2c9q-c2q9-qgqv
    label: security-advisories@github.com
  - url: 'https://github.com/langchain-ai/helm'
  - url: 'https://pypi.org/project/langgraph-api'
  - url: 'https://github.com/advisories/GHSA-2c9q-c2q9-qgqv'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55235'
tags:
  - nvd
  - osv
  - pip
  - cve.org
epss: 0.00365
epssPercentile: 0.2755
aliases:
  - GHSA-2c9q-c2q9-qgqv
  - PYSEC-2026-3857
ecosystem: pip
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-16T15:14:41.906689Z'
ingestedAt: '2026-08-19T19:22:18.276Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-55235)

Affected packages:

- `langgraph-api < 0.10.0`

Patched in:

- `langgraph-api 0.10.0`

Source: https://osv.dev/vulnerability/GHSA-2c9q-c2q9-qgqv