CVE-2026-119415: CakePHP through 5.4.3 MIME Header Injection via FormDataPart Content-Type

CakePHP through 5.4.3 contains a header injection vulnerability in FormDataPart that allows attackers to inject MIME part headers via unsanitized Content-Type and Content-ID values. Attackers can supply CR/LF sequences in attachment MIME types or Content-IDs passed to Message::setAttachments() or HTTP client multipart data to add arbitrary headers or content.