Hono: `validator('form')` skips validation for `multipart/form-data` requests with extra parameters

Summary validator('form') only recognizes a multipart/form-data Content-Type that carries nothing but a single boundary parameter. A request with another legal parameter, such as charset, or with extra whitespace after the ; is not recognized as a form. The validation callback then receives an empty object, while c.req.parseBody() still parses the body as a form. Details The check that decides whether a request body is a form was written as a strict pattern over the whole Content-Type value. Any parameter list that does not look exactly like ; boundary=... fails the check. When it fails, the middleware does not read the body and passes an empty object to the validation callback. If the callback accepts an empty object, the request proceeds to the handler, which can still read all submitted fields through c.req.parseBody() or c.req.formData(). application/x-www-form-urlencoded is not affected. Only the multipart/form-data branch has the strict pattern. This issue arises when an application relies on validator('form') to reject or restrict fields and the validation callback does not fail on an empty object. Impact An unauthenticated client can send form fields that the form…

curl https://cve.zerocrew.in/api/cve/CVE-2026-126356