CVE-2017-14251
Unrestricted File Upload vulnerability in the fileDenyPattern in sysext/core/Classes/Core/SystemEnvironmentBuilder.php in TYPO3 7.6.0 to 7.6.21 and 8.0.0 to 8.7.4 allows remote authenticated users to upload files with a .pht extension and consequently execute arbitrary PHP code.
Source: CVE-2017-14251