[MEDIUM] SS-2016-016: XSS In CMSSecurity BackURL

PKSA-k5zs-4c34-gd54 GHSA-hhvj-mcrx-3vcf

Affected package: silverstripe/framework

Affected version: >=3.1.0,<3.1.21|>=3.2.0,<3.2.6|>=3.3.0,<3.3.4|>=3.4.0,<3.4.2

Reported by:
GitHub, FriendsOfPHP/security-advisories