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

Description

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).

Timeline

Scores

EPSS (exploitation in 30 days)

0.94% · top 39% of all CVEs (14 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.1.

Affected products

• 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

Affected packages

From reviewed advisories of the GitHub Advisory Database.

• NuGetHotChocolate.LanguageGHSA-qr3m-xw4c-jqw3 (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-23579 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisory GHSA-qr3m-xw4c-jqw3 (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-40324](https://cveledger.app/badge/CVE-2026-40324.svg)](https://cveledger.app/cve/CVE-2026-40324)

Record last updated 20 Apr 2026, 16:16 UTC.