{"id":"CVE-2026-109413","aliases":["GHSA-2v3c-qxhr-7vpv"],"url":"https://o3.security/vulnerability/CVE-2026-109413","summary":"Symfony: Unbounded Recursion in the YAML Inline Lexer Lets a Single Document Crash the Process","details":"### Description\n\n`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\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### Resolution\n\nThe inline lexer now enters and leaves the same nesting level as the rest of the parser, so nested inline collections are bounded by `maxNestingLevel`, and the parser raises a `ParseException` beyond it.\n\nThe patches for this issue are available [here](https://github.com/symfony/symfony/commit/2a8bf9c58d862b0c76a35ce288d1ba6a27223aad) for branch 5.4 (and forward-ported to 6.4, 7.4, 8.1 and 8.2).\n\n### Credits\n\nWe would like to thank Nicolas Grekas for reporting the issue and providing the fix.\n\n### References\n\n- Fix: [#65688](https://github.com/symfony/symfony/pull/65688)","published":"2026-10-15T14:57:00.211Z","modified":"2026-10-28T02:30:38.447707121Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"5.4.54"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"6.4.45"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"7.4.18"},{"ecosystem":"Packagist","name":"symfony/symfony","fixedVersion":"8.1.6"},{"ecosystem":"Packagist","name":"symfony/yaml","fixedVersion":"5.4.54"},{"ecosystem":"Packagist","name":"symfony/yaml","fixedVersion":"6.4.45"},{"ecosystem":"Packagist","name":"symfony/yaml","fixedVersion":"7.4.18"},{"ecosystem":"Packagist","name":"symfony/yaml","fixedVersion":"8.1.6"}],"fix":{"url":"https://github.com/symfony/symfony/pull/65688","label":"symfony/symfony#65688"},"references":[{"type":"WEB","url":"https://packagist.org/packages/symfony/yaml"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/109xxx/CVE-2026-109413.json"},{"type":"ADVISORY","url":"https://github.com/symfony/symfony/security/advisories/GHSA-2v3c-qxhr-7vpv"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-109413"},{"type":"ADVISORY","url":"https://symfony.com/blog/cve-2026-109413-unbounded-recursion-in-the-yaml-inline-lexer-lets-a-single-document-crash-the-process"},{"type":"FIX","url":"https://github.com/symfony/symfony/pull/65688"},{"type":"PACKAGE","url":"https://github.com/symfony/yaml"},{"type":"WEB","url":"https://github.com/symfony/symfony/commit/116287c3b5bc057e7a0420d2e52d384e14ea9417"},{"type":"WEB","url":"https://github.com/symfony/symfony/commit/2a8bf9c58d862b0c76a35ce288d1ba6a27223aad"},{"type":"WEB","url":"https://github.com/symfony/symfony/commit/8fb436fed9658a79d220e9f2b1ba8a2095559018"},{"type":"WEB","url":"https://github.com/symfony/symfony/commit/ab61e6cfd35042f16840a00f485eab2481dd4c2a"},{"type":"WEB","url":"https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-109413.yaml"},{"type":"WEB","url":"https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/yaml/CVE-2026-109413.yaml"},{"type":"PACKAGE","url":"https://github.com/symfony/symfony"},{"type":"WEB","url":"https://github.com/symfony/symfony/releases/tag/v5.4.54"},{"type":"WEB","url":"https://github.com/symfony/symfony/releases/tag/v6.4.45"},{"type":"WEB","url":"https://github.com/symfony/symfony/releases/tag/v7.4.18"},{"type":"WEB","url":"https://github.com/symfony/symfony/releases/tag/v8.1.6"},{"type":"WEB","url":"https://symfony.com/cve-2026-109413"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:30:38.447707121Z"}}