Package Instance

Prevent user enumeration using Guard or the new Authenticator-based Security
Description
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The ability to enumerate users was possible without relevant permissions due to different exception messages depending on whether the user existed or not. It was also possible to enumerate users by using a timing attack, by comparing time elapsed when authenticating an existing user and authenticating a non-existing user.

Resolution
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We now ensure that 403s are returned whether the user exists or not if the password is invalid or if the user does not exist.

The patch for this issue is available [here](https://github.com/symfony/symfony/commit/2a581d22cc621b33d5464ed65c4bc2057f72f011) for branch 3.4.

Credits
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I would like to thank James Isaac and Mathias Brodala for reporting the issue and Robin Chalas for fixing the issue.

Cross-Site Request Forgery (CSRF)
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. The Symfony form component provides a CSRF protection mechanism by using a random token injected in the form and using the session to store and control the token submitted by the user. When using the FrameworkBundle, this protection can be enabled or disabled with the configuration. If the configuration is not specified, by default, the mechanism is enabled as long as the session is enabled. In a recent change in the way the configuration is loaded, the default behavior has been dropped and, as a result, the CSRF protection is not enabled in form when not explicitly enabled, which makes the application sensible to CSRF attacks. This issue has been resolved in the patch versions listed and users are advised to update. There are no known workarounds for this issue.

Duplicate
This advisory duplicates another.

RCE in Symfony
Description
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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.

Resolution
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HTTP headers designed for internal use in `HttpCache` are now stripped from remote responses before being passed to `HttpCache`.

The patch for this issue is available [here](https://github.com/symfony/symfony/commit/d9910e0b33a2e0f993abff41c6fbc86951b66d78) for the 4.4 branch.

Credits
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I would like to thank Matthias Pigulla (webfactory GmbH) for reporting and fixing the issue.