CVE-2018-19790: An open redirect was discovered in Symfony 2.7.x before 2.7.50, 2.8.x before 2.8.49, 3.x before 3.4.20, 4.0.x before 4.0.15, 4.1.x before 4.1.9 and 4.2.x before 4.2.1. By using backslashes in the `_failure_path` input field of login forms, an attacker can work around the redirection target restrictions and effectively redirect the user to any domain after login.
CVE-2018-19789: An issue was discovered in Symfony 2.7.x before 2.7.50, 2.8.x before 2.8.49, 3.x before 3.4.20, 4.0.x before 4.0.15, 4.1.x before 4.1.9, and 4.2.x before 4.2.1. When using the scalar type hint `string` in a setter method (e.g. `setName(string $name)`) of a class that's the `data_class` of a form, and when a file upload is submitted to the corresponding field instead of a normal text input, then `UploadedFile::__toString()` is called which will then return and disclose the path of the uploaded file. If combined with a local file inclusion issue in certain circumstances this could escalate it to a Remote Code Execution.
2 issues skipped by the security teams:
CVE-2018-14774: An issue was discovered in HttpKernel in Symfony 2.7.0 through 2.7.48, 2.8.0 through 2.8.43, 3.3.0 through 3.3.17, 3.4.0 through 3.4.13, 4.0.0 through 4.0.13, and 4.1.0 through 4.1.2. When using HttpCache, the values of the X-Forwarded-Host headers are implicitly set as trusted while this should be forbidden, leading to potential host header injection.
CVE-2018-14773: An issue was discovered in Http Foundation in Symfony 2.7.0 through 2.7.48, 2.8.0 through 2.8.43, 3.3.0 through 3.3.17, 3.4.0 through 3.4.13, 4.0.0 through 4.0.13, and 4.1.0 through 4.1.2. It arises from support for a (legacy) IIS header that lets users override the path in the request URL via the X-Original-URL or X-Rewrite-URL HTTP request header. These headers are designed for IIS support, but it's not verified that the server is in fact running IIS, which means anybody who can send these requests to an application can trigger this. This affects \Symfony\Component\HttpFoundation\Request::prepareRequestUri() where X-Original-URL and X_REWRITE_URL are both used. The fix drops support for these methods so that they cannot be used as attack vectors such as web cache poisoning.