CVE-2026-40476

MEDIUM6.9

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

Published Apr 17, 2026

Modified 5 days ago

Details

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.

References

WEB

https://github.com/webonyx/graphql-php/releases/tag/v15.31.5

WEB

https://github.com/webonyx/graphql-php/security/advisories/GHSA-68jq-c3rv-pcrr

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-40476

CVSS Analysis

CVSS v4.0

6.9

Exploitability

Attack Vector