webonyx graphql-php: Unbounded recursion in parser causes stack overflow on crafted nested input

webonyx graphql-php is a PHP implementation of the GraphQL specification. Prior to 15.32.3, GraphQL\Language\Parser performs recursive descent without a recursion limit in parseSelectionSet, parseValueLiteral, and parseTypeReference. A remote attacker can submit deeply nested selection sets, object or list values, or list types that exhaust the PHP process stack during pre-validation parsing, before query validation and complexity controls run. The resulting SIGSEGV can terminate PHP-FPM workers or long-running Swoole, RoadRunner, ReactPHP, or CLI processes and cannot be caught by application-level exception handling. This issue is fixed in version 15.32.3.

Source published

8 Oct 2026 17:49:57 UTC

Source modified

8 Oct 2026 18:39:56 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H