[MEDIUM] CVE-2019-18886: Prevent user enumeration using switch user functionality

PKSA-gtv2-2115-2srw CVE-2019-18886 GHSA-4vpc-5jx4-cfqg

Affected package: symfony/symfony

Affected version: >=4.1.0,<4.2.0|>=4.2.0,<4.2.12|>=4.3.0,<4.3.8

Reported by:
GitHub, FriendsOfPHP/security-advisories