An issue was discovered in the LDAP component in Symfony 2.8.x before 2.8.37, 3.3.x before 3.3.17, 3.4.x before 3.4.7, and 4.0.x before 4.0.7. It allows remote attackers to bypass authentication by logging in with a "null" password and valid username, which triggers an unauthenticated bind. NOTE: this issue exists because of an incomplete fix for CVE-2016-2403.

An issue was discovered in the Security component in Symfony 2.7.x before 2.7.48, 2.8.x before 2.8.41, 3.3.x before 3.3.17, 3.4.x before 3.4.11, and 4.0.x before 4.0.11. By default, a user's session is invalidated when the user is logged out. This behavior can be disabled through the invalidatesession option. In this case, CSRF tokens were not erased during logout which allowed for CSRF token fixation.

An issue was discovered in the Security component in Symfony 2.7.x before 2.7.48, 2.8.x before 2.8.41, 3.3.x before 3.3.17, 3.4.x before 3.4.11, and 4.0.x before 4.0.11. A session fixation vulnerability within the "Guard" login feature may allow an attacker to impersonate a victim towards the web application if the session id value was previously known to the attacker.

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.

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 XREWRITEURL are both used. The fix drops support for these methods so that they cannot be used as attack vectors such as web cache poisoning.

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 failurepath 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-2018-11408: Open redirect vulnerability on security handlers

An issue was discovered in the HttpFoundation component in Symfony 2.7.x before 2.7.48, 2.8.x before 2.8.41, 3.3.x before 3.3.17, 3.4.x before 3.4.11, and 4.0.x before 4.0.11. The PDOSessionHandler class allows storing sessions on a PDO connection. Under some configurations and with a well-crafted payload, it was possible to do a denial of service on a Symfony application without too much resources.

CVE-2021-21424: Prevent user enumeration via response content in authentication mechanisms

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 dataclass 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.