CVE-2026-40476 — graphql-php: Denial of Service via quadratic complexity in OverlappingFieldsCanBeMerged validation

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
webonyx / graphql-php	affected < 15.31.5

CWE

CWE-407

References

https://github.com/webonyx/graphql-php/security/advisories/GHSA-68jq-c3rv-pcrr
https://github.com/webonyx/graphql-php/releases/tag/v15.31.5

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

CVE

No English description supplied.

http://www.openwall.com/lists/oss-security/2026/09/14/26