CVE-2026-40476

Q: How do I fix CVE-2026-40476?

Upgrade graphql-php to 15.31.5 or later.

Q: Is CVE-2026-40476 being actively exploited?

Not that we know of. CVE-2026-40476 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.48% is the estimated probability that it will be exploited in the next 30 days. That is higher than 40% of all scored CVEs.

Q: How severe is CVE-2026-40476?

CVE-2026-40476 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-40476 affect?

Published advisories record a fix for graphql-php (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

HIGH

7.5

CVSS v3

NVD

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.

CWE-407

How to fix

Remediation Available

graphql-phpNVD

Affected:< 15.31.5Fixed in:15.31.5CVE-2026-40476derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.48%probability of exploitation in 30 days

40thpercentile

Low risk: more likely to be exploited than 40% of all known CVEs.

References

Vendor Advisory1

github.com

Release Notes1

github.com

Related Vulnerabilities

Other CWE-407 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-27223	Medium	5.2	78%	-	Fix
CVE-2022-36021	Medium	5.5	60%	-	Fix
CVE-2021-33582	High	7.5	3.1%	-	Fix
CVE-2024-43485	High	7.5	3.1%	-	Fix
CVE-2024-43484	High	7.5	2.9%	-	Fix
CVE-2016-10396	High	7.5	2.9%	-	-

Common questions

How do I fix CVE-2026-40476?

Upgrade graphql-php to 15.31.5 or later.

Is CVE-2026-40476 being actively exploited?

Not that we know of. CVE-2026-40476 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.48% is the estimated probability that it will be exploited in the next 30 days. That is higher than 40% of all scored CVEs.

How severe is CVE-2026-40476?

CVE-2026-40476 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-40476 affect?

Published advisories record a fix for graphql-php (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-21.