CVE-2026-40476Public exploitNetwork attack vector

Service interruption via quadratic field comparisons

Published Apr 17, 2026 · Updated Apr 17, 2026

Algorithmic complexity in WebOnyx graphql-php before 15.31.5 allows remote attackers to interrupt service with repeated GraphQL fields. The collectConflictsWithin() method performs O(n²) pairwise comparisons among fields sharing a response name, even when identical fields produce no conflict. An unauthenticated crafted query can consume CPU before execution and reach a request timeout; QueryDepth and QueryComplexity limits do not block this validation work.

CVSS severity6.9
Medium
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic complexity in WebOnyx graphql-php before 15.31.5 allows remote attackers to interrupt service with repeated GraphQL fields. The collectConflictsWithin() method performs O(n²) pairwise comparisons among fields sharing a response name, even when identical fields produce no conflict. An unauthenticated crafted query can consume CPU before execution and reach a request timeout; QueryDepth and QueryComplexity limits do not block this validation work.

The record

CVE
CVE-2026-40476
Published
Apr 17, 2026
Updated
Apr 17, 2026
Vendor
WebOnyx
Product
graphql-php
Classifications
CWE-407, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 15.31.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WebOnyx · graphql-phpversion=< 15.31.5

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.9GitHubCVSS: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 describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-407Inefficient Algorithmic Complexity
T1499.004Application or System Exploitation

Public exploit references

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Technologies

Your stack

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Your stack

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