Symfony is a PHP framework for web and console applications and a set of reusable PHP components. The ability to enumerate users was possible without relevant permissions due to different handling depending on whether the user existed or not when attempting to use the switch users functionality. We now ensure that 403s are returned whether the user exists or not if a user cannot switch to a user or if the user does not exist. The patch for this issue is available for branch 3.4.

In Symfony before versions 4.4.13 and 5.1.5, the CachingHttpClient class from the HttpClient Symfony component relies on the HttpCache class to handle requests. HttpCache uses internal headers like X-Body-Eval and X-Body-File to control the restoration of cached responses. The class was initially written with surrogate caching and ESI support in mind (all HTTP calls come from a trusted backend in that scenario). But when used by CachingHttpClient and if an attacker can control the response for a request being made by the CachingHttpClient, remote code execution is possible. This has been fixed in versions 4.4.13 and 5.1.5.

In Symfony before versions 5.0.5 and 4.4.5, some properties of the Exception were not properly escaped when the `ErrorHandler` rendered it stacktrace. In addition, the stacktrace were displayed even in a non-debug configuration. The ErrorHandler now escape alls properties of the exception, and the stacktrace is only display in debug configuration. This issue is patched in symfony/http-foundation versions 4.4.5 and 5.0.5

In symfony/security-http before versions 4.4.7 and 5.0.7, when a `Firewall` checks access control rule, it iterate overs each rule's attributes and stops as soon as the accessDecisionManager decides to grant access on the attribute, preventing the check of next attributes that should have been take into account in an unanimous strategy. The accessDecisionManager is now called with all attributes at once, allowing the unanimous strategy being applied on each attribute. This issue is patched in versions 4.4.7 and 5.0.7.

In Symfony before versions 4.4.7 and 5.0.7, when a `Response` does not contain a `Content-Type` header, affected versions of Symfony can fallback to the format defined in the `Accept` header of the request, leading to a possible mismatch between the response's content and `Content-Type` header. When the response is cached, this can prevent the use of the website by other users. This has been patched in versions 4.4.7 and 5.0.7.

Symfony 2.0.X before 2.0.24, 2.1.X before 2.1.12, 2.2.X before 2.2.5, and 2.3.X before 2.3.3 have an issue in the HttpFoundation component. The Host header can be manipulated by an attacker when the framework is generating an absolute URL. A remote attacker could exploit this vulnerability to inject malicious content into the Web application page and conduct various attacks.

An issue was discovered in Symfony 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. Serializing certain cache adapter interfaces could result in remote code injection. This is related to symfony/cache.

An issue was discovered in Symfony 2.8.0 through 2.8.50, 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. If an application passes unvalidated user input as the file for which MIME type validation should occur, then arbitrary arguments are passed to the underlying file command. This is related to symfony/http-foundation (and symfony/mime in 4.3.x).

An issue was discovered in Symfony 2.8.0 through 2.8.50, 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. The UriSigner was subject to timing attacks. This is related to symfony/http-kernel.

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.