{"id":"CVE-2026-109413","published":"2026-10-15T15:17:24.993","lastModified":"2026-10-16T16:00:33.533","description":"In Symfony YAML prior to versions 5.4.54, 6.4.45, 7.4.18, and 8.1.6, Yaml\\Parser::lexInlineStructure() recursed through lexInlineMapping() and lexInlineSequence() for every { and [ of an inline collection, without entering the nesting level that the rest of the parser bounds with maxNestingLevel. A document made of deeply nested inline collections, such as [[[[...]]]], exhausted the stack while it was being lexed: depending on the PHP version and its stack settings, the process crashed or the request ended with a fatal error.\n\n\n\nAny code parsing untrusted YAML is affected. That includes #[MapRequestPayload] when the Yaml component is installed and the endpoint does not restrict acceptFormat: a single unauthenticated request with a YAML content type is enough.\n\n\n\nThis issue affects symfony/yaml through v5.4.53, v6.0.0-BETA1 through v6.4.44, v7.0.0-BETA1 through v7.4.17, and v8.0.0-BETA1 through v8.1.5.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":["CWE-674"],"vendors":[],"products":[],"references":[{"url":"https://github.com/symfony/symfony/pull/65688","tags":[]},{"url":"https://github.com/symfony/symfony/security/advisories/GHSA-2v3c-qxhr-7vpv","tags":[]},{"url":"https://symfony.com/blog/cve-2026-109413-unbounded-recursion-in-the-yaml-inline-lexer-lets-a-single-document-crash-the-process","tags":[]}],"exploitRefs":[{"url":"https://github.com/symfony/symfony/pull/65688","tags":[]},{"url":"https://github.com/symfony/symfony/security/advisories/GHSA-2v3c-qxhr-7vpv","tags":[]}],"hasPoc":true,"ai":null}