CVE-2026-114604

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.

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.

Report metadata

| Field | Value | | --- | --- | | Package | @graphql-tools/utils (npm, pkg:github/ardatan/graphql-tools) | | Repository | https://github.com/ardatan/graphql-tools | | Component | mergeIncrementalResult / setObjectKeyPath (packages/utils/src/mergeIncrementalResult.ts) | | Vulnerability class | Prototype pollution (via unvalidated object path traversal) | | Verified against | Source read at 134d67ae36a559651f43ec7fe4a9da76f4a00c2b; master HEAD ccca0ff0dc8ea20726fd116b2f19a38709c30e62; published npm builds 10.10.0, 10.10.1, 11.0.0, 12.0.0, 12.0.1 | | Affected versions | @graphql-tools/utils >= 10.10.1 through the scanned 12.0.0 source; introduced by fbb58b51c4993ba9680ce6c2ef7203ab3a142713 ("remove dset dependency"). 12.0.1 also reproduces. 10.10.0 does not. | | API surface | Public, documented export (packages/utils/src/index.ts:55) | | Affected in default configuration | Yes — no options are involved; the forbidden-key check in setObjectKeyPath is the only defense and it is on by default |

Summary

mergeIncrementalResult merges an incremental GraphQL response part into an accumulated execution result by walking ['data', ...incrementalResult.path] and assigning at the resolved location. setObjectKeyPath tries to reject dangerous segments with strict string equality against '__proto__', 'constructor' and 'prototype' (lines 50-52 and 60-62), but it never validates that a path segment is a primitive string or number. A JSON path segment such as ["__proto__"] is an array object, so ["__proto__"] !== '__proto__' and the guard passes; the very next statement does current[key], whose ToPropertyKey coercion turns that array into the string key "__proto__" and resolves Object.prototype. The following, innocuous-looking segment is then assigned directly onto Object.prototype.

In a consuming app, incrementalResult is the response part being merged — data parsed from an upstream @defer/@stream multipart or incremental-delivery response from another GraphQL server or transport. The ExecutionResult TypeScript annotation is not a runtime check, so a malicious, compromised, or MITM'd upstream can choose the path value and therefore choose global prototype keys and values in the gateway or client process.

Comparable paths through the same helper, for contrast:

• Plain string segment "__proto__" -> blocked by strict equality, lines 50-52 (confirmed by a control case in testing)
• Array segment ["__proto__"] -> unsafe: passes the guard at lines 50-52, then coerced to the __proto__ key at lines 53-57
• Same operation in 10.10.0 and earlier, which used dset -> not exploitable (0/5 attack payloads succeeded)

Impact

A malicious incremental GraphQL response can add arbitrary properties with attacker-chosen values to Object.prototype in the consuming Node.js process. Because every plain object inherits from it, this can change authorization and configuration checks and the behavior of unrelated code elsewhere in the process — a networked PoC set Object.prototype.isAdmin = true and Object.prototype.ownerEmail, after which a consumer-style check opts.isAdmin === true on a freshly created {} returned true.

The delta over the safe behaviour: without this traversal flaw, a hostile upstream response can only influence the GraphQL data returned to the caller — a bounded, in-band effect. With path: [["__proto__"], "isAdmin"], the write lands on Object.prototype, escaping the response object entirely and affecting objects created later and code that never touches the response.

Scoring note: this report deliberately carries no CVSS vector. No score was produced for it, and exploitability depends on the consuming application's data flow — specifically whether it merges incremental results from an upstream it does not control, and how much it relies on inherited defaults. Consumers who are not affected: anything on…

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.

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.

Report metadata

| Field | Value | | --- | --- | | Package | @graphql-tools/utils (npm, pkg:github/ardatan/graphql-tools) | | Repository | https://github.com/ardatan/graphql-tools | | Component | mergeIncrementalResult / setObjectKeyPath (packages/utils/src/mergeIncrementalResult.ts) | | Vulnerability class | Prototype pollution (via unvalidated object path traversal) | | Verified against | Source read at 134d67ae36a559651f43ec7fe4a9da76f4a00c2b; master HEAD ccca0ff0dc8ea20726fd116b2f19a38709c30e62; published npm builds 10.10.0, 10.10.1, 11.0.0, 12.0.0, 12.0.1 | | Affected versions | @graphql-tools/utils >= 10.10.1 through the scanned 12.0.0 source; introduced by fbb58b51c4993ba9680ce6c2ef7203ab3a142713 ("remove dset dependency"). 12.0.1 also reproduces. 10.10.0 does not. | | API surface | Public, documented export (packages/utils/src/index.ts:55) | | Affected in default configuration | Yes — no options are involved; the forbidden-key check in setObjectKeyPath is the only defense and it is on by default |

Summary

mergeIncrementalResult merges an incremental GraphQL response part into an accumulated execution result by walking ['data', ...incrementalResult.path] and assigning at the resolved location. setObjectKeyPath tries to reject dangerous segments with strict string equality against '__proto__', 'constructor' and 'prototype' (lines 50-52 and 60-62), but it never validates that a path segment is a primitive string or number. A JSON path segment such as ["__proto__"] is an array object, so ["__proto__"] !== '__proto__' and the guard passes; the very next statement does current[key], whose ToPropertyKey coercion turns that array into the string key "__proto__" and resolves Object.prototype. The following, innocuous-looking segment is then assigned directly onto Object.prototype.

In a consuming app, incrementalResult is the response part being merged — data parsed from an upstream @defer/@stream multipart or incremental-delivery response from another GraphQL server or transport. The ExecutionResult TypeScript annotation is not a runtime check, so a malicious, compromised, or MITM'd upstream can choose the path value and therefore choose global prototype keys and values in the gateway or client process.

Comparable paths through the same helper, for contrast:

• Plain string segment "__proto__" -> blocked by strict equality, lines 50-52 (confirmed by a control case in testing)
• Array segment ["__proto__"] -> unsafe: passes the guard at lines 50-52, then coerced to the __proto__ key at lines 53-57
• Same operation in 10.10.0 and earlier, which used dset -> not exploitable (0/5 attack payloads succeeded)

Impact

A malicious incremental GraphQL response can add arbitrary properties with attacker-chosen values to Object.prototype in the consuming Node.js process. Because every plain object inherits from it, this can change authorization and configuration checks and the behavior of unrelated code elsewhere in the process — a networked PoC set Object.prototype.isAdmin = true and Object.prototype.ownerEmail, after which a consumer-style check opts.isAdmin === true on a freshly created {} returned true.

The delta over the safe behaviour: without this traversal flaw, a hostile upstream response can only influence the GraphQL data returned to the caller — a bounded, in-band effect. With path: [["__proto__"], "isAdmin"], the write lands on Object.prototype, escaping the response object entirely and affecting objects created later and code that never touches the response.

Scoring note: this report deliberately carries no CVSS vector. No score was produced for it, and exploitability depends on the consuming application's data flow — specifically whether it merges incremental results from an upstream it does not control, and how much it relies on inherited defaults. Consumers who are not affected: anything on…

TuxCare rebuilt @graphql-tools/utils to address 1 CVE. Fixed in 11.2.2-tuxcare.2.

These are all security issues fixed in the git-bug-0.11.0-4.1 package on the GA media of openSUSE Tumbleweed.

Root has patched CVE-2026-114604 in the @graphql-tools/utils package for Root:npm. Multiple fixed versions available.