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CVE-2026-40476

graphql-php: Denial of Service via quadratic complexity in OverlappingFieldsCanBeMerged validation

CVSS 4.0 6.9 MEDIUMCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-40476

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-40476

Published

graphql-php

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "webonyx",
                    "product": "graphql-php",
                    "versions": [
                        {
                            "version": "< 15.31.5",
                            "status": "affected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON