Improper Isolation or Compartmentalization Affecting @graphql-tools/executor-legacy-ws package, versions <1.1.36
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-GRAPHQLTOOLSEXECUTORLEGACYWS-21802753
- published29 Oct 2026
- disclosed28 Oct 2026
- creditUnknown
Introduced: 28 Oct 2026
NewCVE-2026-118666 (opens in a new tab)How to fix?
Upgrade @graphql-tools/executor-legacy-ws to version 1.1.36 or higher.
Overview
@graphql-tools/executor-legacy-ws is an A set of utils for faster development of GraphQL tools
Affected versions of this package are vulnerable to Improper Isolation or Compartmentalization via buildWSLegacyExecutor in packages/executors/legacy-ws/src/index.ts, where a single shared WebSocket connection and a single mutable onmessage handler are reused across all callers of the same executor instance. When a second caller invokes the executor while the socket is already OPEN, its subscribe() call overwrites the shared websocket.onmessage, detaching the first subscriber's handler entirely. Incoming DATA frames are not validated against the operation id, so the second caller's pending next() resolves with the first caller's subscription payload, and the first caller receives nothing. In a multi-tenant gateway context this produces a verbatim cross-tenant data leak.