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HighVulnerabilityCVE-2026-118668updated 28 Oct 2026, 21:17 UTC

LangGraph API: users can reach other users' stored data

Under certain setups, a logged-in user could read, change, or delete another user's saved data in LangGraph. Only deployments using JavaScript or TypeScript custom login with namespace rewriting are affected.

Fixed in langgraph-api 0.15.0Official, 2 sources
SeverityHighCVSS 8.6 of 10
Being exploited?UnclearNo reports either way yet
Fix available?Yeslanggraph-api 0.15.0 · since 28 Oct 2026
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1Ordinary user logs inAttacker has a normal authenticated account
  2. 2Namespace rewrittenAuth handler rewrites namespace for isolation
  3. 3Rewrite not appliedChange is lost before the Store operation runs
  4. 4Other user's data reachedRead, overwrite, search, or delete succeeds
  5. ResultAttacker accesses another user's data

What happened

In langgraph-api, JavaScript/TypeScript custom authentication Store authorization handlers can return a rewritten namespace that is not applied before the Store operation, letting an authenticated user access another user's Store namespace.

Why it is dangerous: Authenticated ordinary users can read, overwrite, search, or delete other users' Store data, breaking data isolation in multi-user deployments.

Are you affected?

You are affected if you run langgraph-api from 0.1.2 up to (not including) 0.15.0 with JavaScript or TypeScript custom authentication whose Store authorization handler isolates users by rewriting the requested namespace, and multiple users' data is stored through that path.

Package / productAffected versionsFixed in
langgraph-api · pip>= 0.1.2, < 0.15.00.15.0

What to do

  1. Upgrade langgraph-api to 0.15.0 or later
  2. If you cannot upgrade yet, change JavaScript/TypeScript Store authorization handlers to reject unauthorized namespaces instead of rewriting them
  3. Apply that workaround to every Store action the deployment exposes

Timeline

  1. 28 Oct 2026, 21:09 UTC
    Publicly disclosed
  2. 28 Oct 2026, 21:09 UTC
    Reported by GitHub Advisory · GitHub Advisory
  3. 28 Oct 2026, 21:10 UTC
    Picked up by Zero Radar
  4. 28 Oct 2026, 21:17 UTC
    NVD reported on it · NVD

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-118668 · GHSA-4hm6-w6qq-w73v
CVSS
8.6 / 10
Disclosed
28 Oct 2026, 21:09 UTC
On Zero Radar
28 Oct 2026, 21:10 UTC (1 min after disclosure)
Last change
28 Oct 2026, 21:17 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

LangGraph API: users can reach other users' stored data · Zero Radar