---
id: "CVE-2026-118667"
kind: "vulnerability"
aliases: ["CVE-2026-118667", "GHSA-3fx2-cqw9-xr3c"]
title: "LangGraph: Unencoded identifiers in LangGraph SDK v3 streaming can redirect authenticated GET requests"
severity: "medium"
cvss: 4.3
epss: null
exploited: false
status: "open"
category: "ai-tooling"
products: [{"name": "langgraph-sdk", "fixed": ["0.4.6"], "affected": ">= 0.4.0, < 0.4.6", "ecosystem": "pypi"}, {"name": "langgraph", "fixed": ["1.2.14"], "affected": ">= 1.2.3, < 1.2.14", "ecosystem": "pypi"}]
ecosystems: ["pypi"]
tags: ["ai-agents", "ai-tooling", "cwe-22", "langgraph", "python", "self-hosted"]
not_affected_if: ["langgraph-platform", "no-v3-streaming", "trusted-identifiers"]
published_at: "2026-10-28T21:05:47+00:00"
first_seen_at: "2026-10-28T21:07:44+00:00"
updated_at: "2026-10-28T21:09:31+00:00"
sources: [{"source": "ghsa", "url": "https://github.com/advisories/GHSA-3fx2-cqw9-xr3c", "first_seen_at": "2026-10-28T21:07:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-118667", "first_seen_at": "2026-10-28T21:35:45+00:00"}]
---

# LangGraph: Unencoded identifiers in LangGraph SDK v3 streaming can redirect authenticated GET requests

The LangGraph Python SDK v3 streaming client puts caller-supplied thread_id and assistant_id values into request paths without encoding them, so relative path segments can redirect an authenticated GET to another readable path on the same server. An attacker who controls those identifiers can read another response on the configured server, and can control the query string through thread_id, but cannot write.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- pypi:langgraph-sdk affected >= 0.4.0, < 0.4.6 fixed 0.4.6
- pypi:langgraph affected >= 1.2.3, < 1.2.14 fixed 1.2.14

## How to check

- Run `pip show langgraph-sdk` and check whether the version is `0.4.0` through `0.4.5`
- Run `pip show langgraph` and check whether the version is `1.2.3` through `1.2.13` with a vulnerable langgraph-sdk
- Check whether application code passes user-controlled text as thread_id or assistant_id into streaming calls

## Fix

- Upgrade `langgraph-sdk` to `0.4.6` or later
- Upgrade `langgraph` to `1.2.14` or later if you use RemoteGraph, which requires `langgraph-sdk>=0.4.6`

## Timeline

- 2026-10-28T21:07:44+00:00 ghsa https://github.com/advisories/GHSA-3fx2-cqw9-xr3c
- 2026-10-28T21:35:45+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-118667

## From the sources

### Summary

The LangGraph Python SDK v3 streaming client interpolates caller-supplied `thread_id` and `assistant_id` values into request paths without encoding them at four synchronous and asynchronous call sites. Relative path segments can therefore redirect an authenticated GET request to another path on the same configured server.

### Details

The affected `get_tree` and `_fetch_state` implementations build request paths from raw identifiers rather than passing each identifier through the SDK's existing `_quote_path_param` helper. HTTP path normalization can collapse values containing relative segments before dispatch while retaining the client's authentication headers.

`langgraph-sdk` versions 0.4.0 through 0.4.5 are affected. The v3 stream module is not present in the 0.3.x release line.

`RemoteGraph` v3 streaming in `langgraph` 1.2.3 and later is also affected when used with a vulnerable `langgraph-sdk` version. It passes `config["configurable"]["thread_id"]` into `threads.stream(...)`, and its dependency range permits affected SDK versions.

### Impact

An application is affected only if it passes attacker-controlled text as a streaming `thread_id` or `assistant_id`. In that configuration, an attacker may select another readable path on the configured server and cause the SDK to return that response to the application. Through `thread_id`, the attacker can also control the query string, for example by targeting `/store/items?namespace=...&key=...`; `assistant_id` controls only the path. The affected requests are GET operations, so this issue does not provide a write primitive.

The LangGraph Platform is not exposed to this issue.

### Remediation

Upgrade `langgraph-sdk` to version 0.4.6 or later. The fix encodes `assistant_id` in `get_tree` and `thread_id` in `_fetch_state` with `_quote_path_param` in both synchronous and asynchronous stream modules.

If you use `RemoteGraph`, also upgrade `langgraph` to version 1.2.14 or later, which requires `langgraph-sdk>=0.4.6`.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_