CVE-2026-40476 json
graphql-php: Denial of Service via quadratic complexity in OverlappingFieldsCanBeMerged validation
published 6mo ago modified 14d ago also GHSA-68jq-c3rv-pcrr , EUVD-2026-23569
- cvss
- 7.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.8%
- EPSS 0.8% chance of exploitation in 30 days, percentile 58%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- packagist webonyx/graphql-php 15.31.5
- webonyx graphql-php 15.31.5
Is CVE-2026-40476 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 6mo ago
Exploit prediction
0.85% chance of exploitation in the next 30 days, higher than 58% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 6.9 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N |
| CNA | 4.0 | 6.9 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| GitHub | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| packagist | webonyx/graphql-php | <15.31.5 |
15.31.5 |
Affected products
- webonyx graphql-php
Classification
- Weakness
-
- CWE-407 Inefficient Algorithmic Complexity
References
-
github.com
/webonyx/graphql-php/security/advisories/GHSA-68jq-c3rv-pcrr
web, vendor-advisory
-
github.com
/webonyx/graphql-php/releases/tag/v15.31.5
web, release-notes
- openwall.com /lists/oss-security/2026/09/14/26
-
nvd.nist.gov
/vuln/detail/CVE-2026-40476
advisory
-
github.com
/webonyx/graphql-php
package
Sources
- CVE List CVE-2026-40476
- GitHub Advisory GHSA-68jq-c3rv-pcrr
- NVD CVE-2026-40476
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.