What’s Vulnerable › Vulnerabilities

CVE-2026-75507: GraphQL-core: Denial of service via quadratic complexity in the OverlappingFieldsCanBeMerged validation rule

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-22 · updated 2026-10-23
• Weakness: CWE-400

Description

GraphQL-core is a Python port of the GraphQL.js reference implementation. From 3.0.0 until 3.2.12 and 3.3.0rc1, the OverlappingFieldsCanBeMerged rule in specified_rules repeatedly compares fields that share response names and recursively re-compares flattened inline fragments during the validation phase. The prior named-fragment memoization does not cover this path, so nested repeated inline fragments can drive quadratic and worst-case O(n²·m²) CPU work before any resolver or AST-based depth or complexity control runs. An unauthenticated remote attacker can submit a shallow, highly compressible GraphQL query that pins a worker process and can saturate a multi-worker service. This issue is fixed in versions 3.2.12 and 3.3.0rc1.

Affected products

• graphql-python graphql-core: from 3.0.0, < 3.2.12; from 3.3.0a1, < 3.3.0rc1

References

• https://github.com/graphql-python/graphql-core/commit/150e59814d97d12140be005a558c93188ef89198
• https://github.com/graphql-python/graphql-core/commit/29c2753a7ee30a96a4109e7c6add1a2dae0497d7
• https://github.com/graphql-python/graphql-core/releases/tag/v3.2.12
• https://github.com/graphql-python/graphql-core/releases/tag/v3.3.0rc1
• https://github.com/graphql-python/graphql-core/security/advisories/GHSA-vj8h-fx38-h3vc

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