GraphQL Tools has prototype pollution in well-established utility function mergeDeep

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-104852: 0.45% estimated exploitation activity in the next 30 days; percentile 39.30 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Closed by https://github.com/ardatan/graphql-tools/pull/8423 Mitigated in Hive Gateway by https://github.com/graphql-hive/gateway/pull/2600 A client can alias fields to constructor, proto or prototype so that the response keys from two subgraphs collide on those names during result merging. Because mergeDeep recursed through inherited properties, the merge walked {}.constructor to Object, then Object.proto to Function.prototype, and wrote a subgraph-supplied value over Function.prototype.call, breaking every subsequent request in the process until restart. This is remotely triggerable by an unauthenticated client with a single query against any supergraph that merges an object from two subgraphs, which is the ordinary @shareable or entity case, so it is a denial of service rather than a theoretical hardening issue.

Published by the source

5 Oct 2026, 22:56 UTC

Last modified by the source

5 Oct 2026, 23:15 UTC

Source last checked

26 Oct 2026, 13:06 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-7mx3-vvmw-hjmv

2. Revision 3 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-7mx3-vvmw-hjmv

4. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-7mx3-vvmw-hjmv

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# Patch Next advisory brief: CVE-2026-104852

Advisory: GraphQL Tools has prototype pollution in well-established utility function `mergeDeep`
IDs: CVE-2026-104852, GHSA-7mx3-vvmw-hjmv
Record: https://patchnext.com/advisories/cve-2026-104852 (revision 4, source checked 26 Oct 2026, 13:06 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @graphql-tools/utils 12.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @graphql-tools/utils: affected <= 12.0.0; fixed in 12.0.1

## Suggested inspection (read-only)
- `npm ls @graphql-tools/utils --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @graphql-tools/utils.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-7mx3-vvmw-hjmv (GitHub-reviewed advisory GHSA-7mx3-vvmw-hjmv lists affected ranges: npm @graphql-tools/utils >=0 <=12.0.0)
- Verified: https://osv.dev/vulnerability/GHSA-7mx3-vvmw-hjmv (OSV record GHSA-7mx3-vvmw-hjmv lists affected ranges: npm @graphql-tools/utils >=0 <12.0.1 (fixed))

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