1. Restored the mandatory file (/usr/syno/bin/zip) that has been removed due to Antivirus Essential's false-positive detection.
2. Upgraded Apache HTTP Server to 2.2.31 to address one security vulnerability (CVE-2015-3183).
3. Upgraded PHP to 5.5.28 to address two security vulnerabilities (CVE-2015-5589 and CVE-2015-5590).
4. Fixed two security vulnerabilities to prevent cross-site scripting (XSS) attacks.
5. Fixed a security vulnerability of PCRE library (ASA-201508-11).
6. Fixed an issue where DSM cannot be updated after system recovery on certain models (DS2415+, DS1815+, DS1515+, RS815RP+, RS815+, DS415+).