CVE-2026-104852

High

Description

GraphQL Tools provides utilities for building, stitching, and mocking GraphQL schemas. Prior to 12.0.1, the GraphQL Tools utils package's mergeDeep function follows inherited properties while recursively merging source objects and does not exclude __proto__, constructor, or prototype keys. An unauthenticated GraphQL client can alias fields to those names so responses from two subgraphs collide during ordinary supergraph result merging, causing mergeDeep to traverse Object and Function prototypes and overwrite Function.prototype.call with a subgraph-supplied value. This breaks subsequent requests in the process until restart. This issue is fixed in version 12.0.1.

SeverityHigh
CVSS8.2
Exploit probability—
Product@graphql-tools/utils
PublishedOct 5, 2026
First seenOct 5, 2026

How to fix

Update
  • @graphql-tools/utils12.0.1 or later

Affected products

ProductAffected versionsFixed in
@graphql-tools/utilsnpmv < 12.0.112.0.1

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