---
title: LangGraph API ignored namespace rewrites from JavaScript/TypeScript auth handlers, so one authenticated user could read, overwrite or delete another user's agent Store data (CVE-2026-118668) | ctxsec
url: https://ctxsec.com/items/langgraph-api-cve-2026-118668-js-auth-store-namespace-cross-user
description: ""
status: "official (LangChain GitHub advisory, Oct 28, rated high); finder Coinspect per its Oct 29 post"
published: 2026-10-29
---

> 

[← Context & Harness Attacks](/context) · [markdown](/items/langgraph-api-cve-2026-118668-js-auth-store-namespace-cross-user.md)

official (LangChain GitHub advisory, Oct 28, rated high); finder Coinspect per its Oct 29 post

2026-10-29

### LangGraph API ignored namespace rewrites from JavaScript/TypeScript auth handlers, so one authenticated user could read, overwrite or delete another user's agent Store data (CVE-2026-118668)

In `langgraph-api` 0.1.2 up to (not including) 0.15.0, when a deployment used JavaScript or TypeScript custom authentication and its Store handler limited users by _rewriting_ the requested namespace to their own, the rewrite was dropped before the Store operation ran. An ordinary authenticated user could then read, overwrite, search or delete other users' long-term agent memory and data. No admin rights, user interaction or race is needed.

- **Not affected:** Python auth handlers, and JS/TS handlers that reject unauthorized namespaces instead of rewriting them.
- **Fixed:** `langgraph-api` 0.15.0 carries the handler's changes across the runtime boundary, validates the resulting namespace and rejects malformed changes.
- **Workaround:** change every Store action handler to deny requests for namespaces the user does not own.

**Context:** this is the second LangGraph Store isolation bug on this site in a week (see CVE-2026-115883, Oct 24). If you run multi-tenant agents on LangGraph, test isolation with two real user accounts after upgrading, and check Store logs for cross-namespace reads.

Sources: [GitHub advisory GHSA-4hm6-w6qq-w73v: LangGraph JavaScript custom authentication may permit cross-user Store access, CVE-2026-118668 (Oct 28)](https://github.com/langchain-ai/langgraph/security/advisories/GHSA-4hm6-w6qq-w73v) · [Coinspect on X: CVE-2026-118668 case study (Oct 29)](https://x.com/coinspect/status/2115890649056887129) · [ctxsec: LangGraph Store namespace cross-tenant bug (Oct 24)](https://ctxsec.com/items/langgraph-store-namespace-dot-cross-tenant-cve-2026-115883)