CVE-2026-40324 (GCVE-0-2026-40324)
Vulnerability from cvelistv5 – Published: 2026-04-17 23:05 – Updated: 2026-04-17 23:05
VLAI?
Title
Hot Chocolate's Utf8GraphQLParser has Stack Overflow via Deeply Nested GraphQL Documents
Summary
Hot Chocolate is an open-source GraphQL server. Prior to versions 12.22.7, 13.9.16, 14.3.1, and 15.1.14, Hot Chocolate's recursive descent parser `Utf8GraphQLParser` has no recursion depth limit. A crafted GraphQL document with deeply nested selection sets, object values, list values, or list types can trigger a `StackOverflowException` on payloads as small as 40 KB. Because `StackOverflowException` is uncatchable in .NET (since .NET 2.0), the entire worker process is terminated immediately. All in-flight HTTP requests, background `IHostedService` tasks, and open WebSocket subscriptions on that worker are dropped. The orchestrator (Kubernetes, IIS, etc.) must restart the process. This occurs before any validation rules run — `MaxExecutionDepth`, complexity analyzers, persisted query allow-lists, and custom `IDocumentValidatorRule` implementations cannot intercept the crash because `Utf8GraphQLParser.Parse` is invoked before validation. The `MaxAllowedFields=2048` limit does not help because the crashing payloads contain very few fields. The fix in versions 12.22.7, 13.9.16, 14.3.1, and 15.1.14 adds a `MaxAllowedRecursionDepth` option to `ParserOptions` with a safe default, and enforces it across all recursive parser methods (`ParseSelectionSet`, `ParseValueLiteral`, `ParseObject`, `ParseList`, `ParseTypeReference`, etc.). When the limit is exceeded, a catchable `SyntaxException` is thrown instead of overflowing the stack. There is no application-level workaround. `StackOverflowException` cannot be caught in .NET. The only mitigation is to upgrade to a patched version. Operators can reduce (but not eliminate) risk by limiting HTTP request body size at the reverse proxy or load balancer layer, though the smallest crashing payload (40 KB) is well below most default body size limits and is highly compressible (~few hundred bytes via gzip).
Severity ?
9.1 (Critical)
CWE
- CWE-674 - Uncontrolled Recursion
Assigner
References
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Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| ChilliCream | graphql-platform |
Affected:
< 12.22.7
Affected: >= 13.0.0, < 13.9.16 Affected: >= 14.0.0, < 14.3.1 Affected: >= 15.0.0, < 15.1.14 |
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},
{
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"version": "\u003e= 13.0.0, \u003c 13.9.16"
},
{
"status": "affected",
"version": "\u003e= 14.0.0, \u003c 14.3.1"
},
{
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}
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],
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"discovery": "UNKNOWN"
},
"title": "Hot Chocolate\u0027s Utf8GraphQLParser has Stack Overflow via Deeply Nested GraphQL Documents"
}
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}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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