CVE-2026-40324Hot Chocolate's Utf8GraphQLParser has Stack Overflow via Deeply Nested GraphQL Documents

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).

CVSS

9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Weakness (CWE)

CWE-674

Known exploited

Not in CISA's KEV catalog

EPSS (exploitation in the next 30 days)

Not loaded for this CVE

Assigned by

GitHub_M

NVD analysis

Deferred

Record last updated

Apr 20, 2026

First seen by InfoSec Signals

Oct 9, 2026

The CVE record on cve.org · NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.