What’s Vulnerable › Vulnerabilities

CVE-2026-118666: GraphQL Tools: Shared legacy executor routes one subscription's results to a different caller

• Severity: medium (CVSS 6.0 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-28 · updated 2026-10-29
• Weakness: CWE-200

Description

GraphQL Tools provides utilities for building, stitching, and mocking GraphQL schemas. Prior to version 1.1.36 of the GraphQL Tools legacy WebSocket executor package, buildWSLegacyExecutor in packages/executors/legacy-ws/src/index.ts reuses one WebSocket and replaces its single websocket.onmessage handler whenever a new overlapping subscription starts. The handler delivers LEGACY_WS.DATA frames to the newest observer without comparing data.id with the subscription operation id, so a caller using the same executor can receive another user's authorized subscription payload while the earlier caller's stream is starved. This issue is fixed in version 1.1.36 of the GraphQL Tools legacy WebSocket executor package.

Affected products

• @graphql-tools executor-legacy-ws: before 1.1.36
• ardatan graphql-tools: before 9.0.36

References

• https://github.com/ardatan/graphql-tools/commit/c2f226e6f68236be9e4a577f29faeaa92547458b
• https://github.com/ardatan/graphql-tools/pull/8480
• https://github.com/ardatan/graphql-tools/releases/tag/@graphql-tools/executor-legacy-ws@1.1.36
• https://github.com/ardatan/graphql-tools/security/advisories/GHSA-mp66-8ww2-pcwm

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