CVE-2026-40476

Analyzed Analyzed - Analysis Complete

Quadratic CPU Exhaustion in graphql-go OverlappingFields Validation

Publication date: 2026-04-17

Last updated on: 2026-05-21

Assigner: GitHub, Inc.

Description

graphql-go is a Go implementation of GraphQL. In versions 15.31.4 and below, the OverlappingFieldsCanBeMerged validation rule performs O(n²) pairwise comparisons of fields sharing the same response name. An attacker can send a query with thousands of repeated identical fields, causing excessive CPU usage during validation before execution begins. This is not mitigated by existing QueryDepth or QueryComplexity rules. This issue has been fixed in version 15.31.5.

CVSS Scores

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Meta Information

Published

2026-04-17

Last Modified

2026-05-21

Generated

2026-07-06

AI Q&A

2026-04-18

EPSS Evaluated

2026-07-05

NVD

CVE-2026-40476

Affected Vendors & Products

Vendor	Product	Version / Range
webonyx	graphql-php	to 15.31.5 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-407	An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

Attack-Flow Graph

Executive Summary

The vulnerability exists in graphql-go versions 15.31.4 and below, specifically in the OverlappingFieldsCanBeMerged validation rule. This rule performs O(n²) pairwise comparisons of fields that share the same response name. An attacker can exploit this by sending a query containing thousands of repeated identical fields, which causes excessive CPU usage during the validation phase before query execution.

This excessive CPU usage can degrade performance or potentially lead to denial of service conditions. The issue is not mitigated by existing QueryDepth or QueryComplexity rules and has been fixed in version 15.31.5.

Impact Analysis

This vulnerability can lead to excessive CPU consumption when processing specially crafted GraphQL queries with many repeated identical fields. This can degrade the performance of your application or service, potentially causing slowdowns or denial of service conditions during query validation.

Mitigation Strategies

To mitigate this vulnerability, upgrade graphql-go to version 15.31.5 or later, where the issue has been fixed.

Compliance Impact

The vulnerability in graphql-go allows an attacker to cause excessive CPU usage by sending queries with thousands of repeated identical fields, leading to potential denial of service during validation. However, there is no information provided about how this vulnerability impacts compliance with common standards and regulations such as GDPR or HIPAA.

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