CVE-2026-40476
CVE-2026-40476 is a high-severity vulnerability in Webonyx Graphql-php with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-407.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- CVSS v4: 6.9
- EPSS exploit prediction: 0% (38th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-23569
- Weakness: CWE-407
- Affected product: Webonyx Graphql-php
- Published:
- Last modified:
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.
Frequently asked questions
- What is 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.
- How severe is CVE-2026-40476?
- CVE-2026-40476 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2026-40476 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-40476?
- CVE-2026-40476 affects Webonyx Graphql-php. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-40476?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-40476 have an EU (EUVD) identifier?
- Yes. CVE-2026-40476 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23569.
- When was CVE-2026-40476 published?
- CVE-2026-40476 was published on 2026-04-17 and last updated on 2026-06-17.
References
- https://github.com/webonyx/graphql-php/releases/tag/v15.31.5
- https://github.com/webonyx/graphql-php/security/advisories/GHSA-68jq-c3rv-pcrr
Affected products (1)
- cpe:2.3:a:webonyx:graphql-php:*:*:*:*:*:*:*:*
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