An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

An issue was discovered in Symfony 2.8.0 through 2.8.50, 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. The UriSigner was subject to timing attacks. This is related to symfony/http-kernel.

An issue was discovered in Symfony 2.8.0 through 2.8.50, 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. If an application passes unvalidated user input as the file for which MIME type validation should occur, then arbitrary arguments are passed to the underlying file command. This is related to symfony/http-foundation (and symfony/mime in 4.3.x).

An issue was discovered in Symfony 3.4.0 through 3.4.34, 4.2.0 through 4.2.11, and 4.3.0 through 4.3.7. Serializing certain cache adapter interfaces could result in remote code injection. This is related to symfony/cache.

An issue was discovered in Symfony before 4.2.12 and 4.3.x before 4.3.8. The VarExport component incorrectly escapes strings, allowing some specially crafted ones to escalate to execution of arbitrary PHP code. This is related to symfony/var-exporter.