CVE-2026-55236 langgraph-api: Incomplete assistant authorization in LangGraph Server run creation
Low-privileged users can access private assistant metadata and execute runs using other users' configurations in LangGraph Server deployments with specific custom authorization handlers.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55236?
CVE-2026-55236 is a medium-severity missing authorization vulnerability in langchain-ai langgraph-api, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
langgraph-api implements the LangGraph API for rapid development and testing. Prior to 0.10.0, the langgraph-api run-creation path authorizes the assistant attached to a run by dispatching assistants.search with an incomplete value instead of the assistants.read event used by direct reads and cron creation. In deployments with custom resource handlers that register only assistants.read, omit an assistants.search handler, and have no global fallback handler, no applicable handler supplies an owner filter, allowing a low-privileged user to reference another user's private assistant through POST /runs or POST /threads/{thread_id}/runs. The run-creation response can disclose the private assistant's metadata, config, and context, and the run can execute using that assistant's configuration. Deployments without custom authorization handlers, or with an equivalent owner filter applied through a global handler or across all assistant events, are not affected. This issue is fixed in version 0.10.0.
Weakness: CWE-285
Which versions are affected by CVE-2026-55236?
3 open source packages ship an affected version, including langgraph-api.
| Package | Affected | Fixed in |
|---|---|---|
langgraph-api PyPI | All versions | 0.10.0 |
langgraph-api PyPI | All versions | 0.10.0 |
langgraph-api PyPI | All versions | 0.10.0 |
How do I fix CVE-2026-55236?
Upgrade langgraph-api to 0.10.0 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-55236 being exploited?
There is no known exploitation of CVE-2026-55236 in the wild and no public exploit code.
Sources
Also known as GHSA-jfj5-wrj9-63x4, PYSEC-2026-3858.