{"id":"CVE-2026-109413","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-109413","generatedAt":"2026-10-28T13:13:08.354Z","title":"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.","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.","published":"2026-10-15T15:17:25.000Z","lastModified":"2026-10-16T16:00:34.000Z","status":"Awaiting Analysis","sourceIdentifier":"596c5446-0ce5-4ba2-aa66-48b3b757a647","cvss":{"version":"4.0","score":8.7,"severity":"HIGH","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-674"],"affected":[],"epss":{"score":0.00395,"percentile":0.33582,"date":"2026-10-27","history":[{"date":"2026-10-16","score":0.00507,"percentile":0.41892}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.40%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-15T15:17:25.000Z","detail":{"score":"8.7","severity":"HIGH","publishedAt":"2026-10-15T15:17:24.993Z"},"summary":"New CVE, high severity (CVSS 8.7)."}],"references":[{"url":"https://github.com/symfony/symfony/pull/65688","source":"596c5446-0ce5-4ba2-aa66-48b3b757a647"},{"url":"https://github.com/symfony/symfony/security/advisories/GHSA-2v3c-qxhr-7vpv","source":"596c5446-0ce5-4ba2-aa66-48b3b757a647"},{"url":"https://symfony.com/blog/cve-2026-109413-unbounded-recursion-in-the-yaml-inline-lexer-lets-a-single-document-crash-the-process","source":"596c5446-0ce5-4ba2-aa66-48b3b757a647"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-109413","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}