Package Instance

Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
`Symfony/Http-Kernel` is the HTTP kernel component for Symfony, a PHP framework for web and console applications and a set of reusable PHP components. Headers that are not part of the `trusted_headers` allowed list are ignored and protect users from Cache poisoning attacks. In Symfony, maintainers added support for the `X-Forwarded-Prefix` headers, but this header was accessible in SubRequest, even if it was not part of the `trusted_headers` allowed list. An attacker could leverage this opportunity to forge requests containing a `X-Forwarded-Prefix` header, leading to a web cache poisoning issue.

Duplicate
This advisory duplicates another.

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.