CVE-2026-123824CVE-2026-123824

The Symfony Config component XmlUtils::parse() enables DTD validation before rejecting documents that carry a doctype, allowing XML external entity (XXE) injection in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11. A remote attacker who can supply XML to this method can determine whether local files exist, cause a denial of service, and, in some configurations, exfiltrate local file content via a crafted XML document whose doctype declares an external file:// entity. XmlUtils::parse() sets $dom->validateOnParse = true before calling loadXML() and only rejects documents carrying a doctype afterwards. Enabling DTD validation makes libxml resolve external entities during loadXML(), and LIBXML_NONET blocks http:// but not file://, so a file:// entity is read from disk before the doctype rejection runs. The content of the file is not returned to the caller, but the distinct libxml error for a missing path reveals whether a file exists, an