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Vulnerabilities

Vulnerability · CVE-2026-75507

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

Published Oct 22, 2026 · catalog updated Oct 22, 2026 · Red Hat Red Hat Enterprise Linux

Last checked Nov 3, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-75507. EPSS is 0.60%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.60%
Remediation
Version ranges on file
Affected products
PyPI graphql-core · package pip · pip graphql-core · pypi graphql-core

### Summary The validation rule can be driven into quadratic — and in the worst case — running time by a small, highly compressible query. A single 364 KB document can occupy one CPU core for over five minutes during *validation*, before any resolver runs. Because the rule is part of and therefore enabled by default, every GraphQL-core based server is affected at default settings. ### Details compares every pair of fields that share a response name and recurses into their sub-selections. The memoization added for CVE-2023-26144 ( ) is keyed by **named fragment** identity, so it does not cover this path: inline fragments are flattened into the parent selection set before the cache is consulted, and therefore every pair is re-compared from scratch at every nesting level. Repeating an inline fragment that selects the same response name at two nesting levels multiplies the two effects. There was no comparison budget and no validation timeout, so the rule ran to completion regardless of cost. The cost is incurred in the **validation phase**, which is what makes this hard to defend against from outside the library: query-depth limiters, complexity analyzers and cost estimators all operate on the parsed document *after* validation, and the malicious document is trivially shallow (depth 3, complexity 1). The payload is also one short string repeated many times, so it compresses to a few kilobytes and slips past body-size limits and WAF inspection that only see the compressed request. ### Proof of concept Measured on GraphQL-core 3.2.8 / CPython 3.12 / Linux x86_64: | n | m | query size | validation time | |---|---|---|---| | 20 | 20 | 7.6 KB | 0.16 s | | 50 | 50 | 46 KB | 5.2 s | | 100 | 100 | 182 KB | 81 s | | 200 | 100 | 364 KB | **319 s** | Doubling at fixed quadruples the time, as expected for a quadratic outer loop driving a quadratic inner walk. ### Impact Denial of service. One request pins one worker process for minutes; because CPython holds the GIL for this pure-C

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • PyPI graphql-core3.0.0 → 3.2.12
  • PyPI graphql-core3.3.0a1 → 3.3.0rc1
  • package pipversion unspecified
  • pip graphql-core>= 3.0.0, < 3.2.12
  • pip graphql-core>= 3.3.0a1, < 3.3.0rc1
  • pypi graphql-coreversion unspecified

How to fix CVE-2026-75507

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-75507. EPSS is 0.60%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Which versions are affected?

Compare what you have installed with 3.0.0 → 3.2.12, 3.3.0a1 → 3.3.0rc1, >= 3.0.0, < 3.2.12, >= 3.3.0a1, < 3.3.0rc1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-400: Uncontrolled Resource Consumption; CWE-407; CWE-770: Allocation of Resources Without Limits or Throttling. EPSS 0.60%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 22, 2026 · Red Hat Security Data

    Detected

    graphql-core: graphql-core: Denial of Service via nested inline fragments during query validation

  2. Oct 22, 2026 · GitHub Advisory Database

    Updated

    ### Summary The validation rule can be driven into quadratic — and in the worst case — running time by a small, highly compressible query. A single 364 KB document can occupy one CPU core for over five minutes during *validation*, before any resolver runs. Because the rule is part of and therefore enabled by default, every GraphQL-core based server is affected at default settings. ### Details comp

  3. Oct 22, 2026 · PyPA Advisory Database

    Fix available

    graphql-core fixed in 3.2.12; graphql-core fixed in 3.3.0rc1

  4. Oct 22, 2026 · PyPA Advisory Database

    Fix available

    graphql-core fixed in 3.2.12

  5. Oct 22, 2026 · PyPA Advisory Database

    Fix available

    graphql-core fixed in 3.3.0rc1

  6. Oct 22, 2026 · PyPA Advisory Database

    Updated

    ### Summary The validation rule can be driven into quadratic — and in the worst case — running time by a small, highly compressible query. A single 364 KB document can occupy one CPU core for over five minutes during *validation*, before any resolver runs. Because the rule is part of and therefore enabled by default, every GraphQL-core based server is affected at default settings. ### Details comp

Sources

  • CVE.orgVulnerability recordCVE-2026-75507

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-75507

    30-day exploitation probability 0.60%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-vj8h-fx38-h3vc

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

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-75507

    The OverlappingFieldsCanBeMerged validation rule can be driven into quadratic — and in the worst case O(n²·m²) — running time by a small, highly compressible query. A single 364 KB document can occupy one CPU core for over five minutes during validation, before any resolver runs. Because the rule is part of specified_rules and therefore enabled by default, every GraphQL-core based server is affect

    advisories.gitlab.com
  • PyPA Advisory DatabasePackage advisoryGHSA-vj8h-fx38-h3vc

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

    osv.dev
  • Red Hat Security DataVendor advisoryCVE-2026-75507

    graphql-core: graphql-core: Denial of Service via nested inline fragments during query validation

    access.redhat.com
  • Snyk Vulnerability DatabasePackage advisorySNYK-PYTHON-GRAPHQLCORE-21433568

    Inefficient Algorithmic Complexity

    security.snyk.io

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 28, 2026
  • Snyk Vulnerability DatabaseOct 25, 2026
  • GitHub Advisory DatabaseOct 23, 2026
  • PyPA Advisory DatabaseOct 23, 2026
  • GitLab Advisory DatabaseOct 23, 2026
  • Red Hat Security DataOct 23, 2026
  • CVE.orgOct 23, 2026