Astro is a web framework for content-driven websites. In affected versions a bug in Astro’s CSRF-protection middleware allows requests to bypass CSRF checks. When the `security.checkOrigin` configuration option is set to `true`, Astro middleware will perform a CSRF check. However, a vulnerability exists that can bypass this security. A semicolon-delimited parameter is allowed after the type in `Content-Type`. Web browsers will treat a `Content-Type` such as `application/x-www-form-urlencoded; abc` as a `simple request` and will not perform preflight validation. In this case, CSRF is not blocked as expected. Additionally, the `Content-Type` header is not required for a request. This issue has been addressed in version 4.16.17 and all users are advised to upgrade. There are no known workarounds for this vulnerability.
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.