In versions of Zend Server 8.5 and prior to version 9.2 a format string injection was discovered.

Reported by Dylan Marino

Zend Framework 1.11.3 in Zend Server CE 5.1.0 allows remote attackers to obtain sensitive information via a direct request to a .php file, which reveals the installation path in an error message, as demonstrated by Validate.php and certain other files.

DISPUTED Untrusted search path vulnerability in the installation functionality in Zend Server 5.6.0 SP4, when installed in the top-level C:\ directory, might allow local users to gain privileges via a Trojan horse DLL in the C:\Zend\ZendServer\share\ZendFramework\bin directory, which may be added to the PATH system environment variable by an administrator, as demonstrated by a Trojan horse wlbsctrl.dll file used by the "IKE and AuthIP IPsec Keying Modules" system service in Windows Vista SP1, Windows Server 2008 SP2, Windows 7 SP1, and Windows 8 Release Preview. NOTE: CVE disputes this issue because the choice of C:\ (and the resulting unsafe PATH) is established by an administrative action that is not a default part of the Zend Server installation.

Zend Debugger in Zend Server before 9.1.3 has XSS, aka ZSR-2455.