---
id: CVE-2026-75507
title: >-
  GraphQL-core: Denial of service via quadratic complexity in the
  OverlappingFieldsCanBeMerged validation rule
summary: >-
  GraphQL-core is a Python port of the GraphQL.js reference implementation. From
  3.0.0 until 3.2.12 and 3.3.0rc1, the OverlappingFieldsCanBeMerged rule in
  specified_rules repeatedly compares fields that share response names and
  recursively…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-400
  - CWE-407
vendor: graphql-python
product: graphql-core
affected:
  - 'graphql-core >= 3.0.0, < 3.2.12'
  - 'graphql-core >= 3.3.0a1, < 3.3.0rc1'
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-23T17:32:54.760212Z'
published: '2026-10-22'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T21:08:40.217Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-75507'
references:
  - url: >-
      https://github.com/graphql-python/graphql-core/security/advisories/GHSA-vj8h-fx38-h3vc
    label: >-
      https://github.com/graphql-python/graphql-core/security/advisories/GHSA-vj8h-fx38-h3vc
  - url: >-
      https://github.com/graphql-python/graphql-core/commit/150e59814d97d12140be005a558c93188ef89198
    label: >-
      https://github.com/graphql-python/graphql-core/commit/150e59814d97d12140be005a558c93188ef89198
  - url: >-
      https://github.com/graphql-python/graphql-core/commit/29c2753a7ee30a96a4109e7c6add1a2dae0497d7
    label: >-
      https://github.com/graphql-python/graphql-core/commit/29c2753a7ee30a96a4109e7c6add1a2dae0497d7
  - url: 'https://github.com/graphql-python/graphql-core/releases/tag/v3.2.12'
    label: 'https://github.com/graphql-python/graphql-core/releases/tag/v3.2.12'
  - url: 'https://github.com/graphql-python/graphql-core/releases/tag/v3.3.0rc1'
    label: 'https://github.com/graphql-python/graphql-core/releases/tag/v3.3.0rc1'
  - url: 'https://github.com/graphql-python/graphql-core'
  - url: 'https://github.com/advisories/GHSA-vj8h-fx38-h3vc'
tags:
  - cve.org
  - osv
  - pip
  - ghsa
epss: 0.006
epssPercentile: 0.48503
aliases:
  - GHSA-vj8h-fx38-h3vc
ecosystem: pip
patched:
  - graphql-core 3.2.12
  - graphql-core 3.3.0rc1
ingestedAt: '2026-10-22T22:00:50.254Z'
---

## Overview

GraphQL-core is a Python port of the GraphQL.js reference implementation. From 3.0.0 until 3.2.12 and 3.3.0rc1, the OverlappingFieldsCanBeMerged rule in specified_rules repeatedly compares fields that share response names and recursively re-compares flattened inline fragments during the validation phase. The prior named-fragment memoization does not cover this path, so nested repeated inline fragments can drive quadratic and worst-case O(n²·m²) CPU work before any resolver or AST-based depth or complexity control runs. An unauthenticated remote attacker can submit a shallow, highly compressible GraphQL query that pins a worker process and can saturate a multi-worker service. This issue is fixed in versions 3.2.12 and 3.3.0rc1.

## Affected

- `graphql-core >= 3.0.0, < 3.2.12`
- `graphql-core >= 3.3.0a1, < 3.3.0rc1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-75507)

Affected packages:

- `graphql-core >= 3.0.0, < 3.2.12`
- `graphql-core >= 3.3.0a1, < 3.3.0rc1`

Patched in:

- `graphql-core 3.2.12`
- `graphql-core 3.3.0rc1`

Source: https://osv.dev/vulnerability/GHSA-vj8h-fx38-h3vc