Black Friday 2021 Offers 30% discount on Certification, Coaching, and SymfonyInsight Teams subscriptions

CVE-2019-18886: Prevent user enumeration using switch user functionality

Affected versions

Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7 versions of the Symfony Security/Http component are affected by this security issue.

The issue has been fixed in Symfony 4.2.12 and 4.3.8.

Note that no fixes are provided for Symfony 4.1 as they are not maintained anymore.


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 here for branch 4.2.


I would like to thank Matt Daum for reporting & Nicolas Grekas for fixing the issue.

Manage your notification preferences to receive an email as soon as a Symfony security release is published.
If you have found a security issue in Symfony, please send the details to security [at] and don't disclose it publicly until we can provide a fix for it.
Help the Symfony project!

As with any Open-Source project, contributing code or documentation is the most common way to help, but we also have a wide range of sponsoring opportunities.

CVE-2019-18886: Prevent user enumeration using switch user functionality

Tweet this


Comments are closed.

To ensure that comments stay relevant, they are closed for old posts.