Symfony 2.7.0 to 2.7.50, 2.8.0 to 2.8.49, 3.4.0 to 3.4.25, 4.1.0 to 4.1.11 and 4.2.0 to 4.2.6 versions of the Symfony Dependency Injection component are affected by this security issue.
The issue has been fixed in Symfony 2.7.51, 2.8.50, 3.4.26, 4.1.12 and 4.2.7.
Note that no fixes are provided for Symfony 3.0, 3.1, 3.2, 3.3, and 4.0 as they are not maintained anymore.
Service IDs derived from unfiltered user input could result in the execution of any arbitrary code, resulting in possible remote code execution.
On setting of an alias or a service we both confirm that the id does not contain certain characters and that ids are escaped while being dumped.
The patch for this issue is available here for branch 3.4.
I would like to thank Nicolas Grekas for reporting & fixing the issue.
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