GraphQL Tools provides utilities for building, stitching, and mocking GraphQL schemas. From 10.10.1 until 12.0.2, the @graphql-tools/utils mergeIncrementalResult helper passes incrementalResult.path segments to setObjectKeyPath without runtime primitive-type validation. A non-primitive segment can bypass strict comparisons against __proto__, constructor, and prototype, then be coerced during property access so a malicious or compromised upstream incremental GraphQL response writes attacker-controlled properties to Object.prototype in the consuming Node.js process. The affected implementation is packages/utils/src/mergeIncrementalResult.ts and is reachable when consumers merge untrusted @defer or @stream transport results. This issue is fixed in version 12.0.2.
https://github.com/ardatan/graphql-tools/security/advisories/GHSA-c4qx-w738-7hr3
https://github.com/ardatan/graphql-tools/releases/tag/@graphql-tools/[email protected]
https://github.com/ardatan/graphql-tools/pull/8467
https://github.com/ardatan/graphql-tools/commit/20d36a5c6eb8fd5524420988e01a48618c450d70
https://github.com/ardatan/graphql-tools/commit/19f5b3373fd7ace0688d19950fc529ce8347952a
Published: 2026-11-05
Updated: 2026-11-09
Named Vulnerability: GHSA-c4qx-w738-7hr3
Base Score: 7.5
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P
Severity: High
Base Score: 9.8
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: Critical
Base Score: 8.4
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00521