CVE-2026-40476

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 4.0

6.9CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.6% chance of exploitation in the next 30 days; higher than 50% of CVEs (scores of 2026-10-26)

CWE

CWE-407

Published

2026-04-17

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• webonyx:graphql-php

References

• https://github.com/webonyx/graphql-php/releases/tag/v15.31.5
• https://github.com/webonyx/graphql-php/security/advisories/GHSA-68jq-c3rv-pcrr
• http://www.openwall.com/lists/oss-security/2026/09/14/26

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