Next leap second adjustment is scheduled for 30th of June 2015 at 23:59:60 UTC and it may cause issues on NTP synchronized devices and operating systems. Systems based on older Linux kernels are known to be affected by leap second, several vendors have released KB articles regarding leap second impact on their software.
Certain versions of VMware vCenter Server Appliance 5.0 and 5.1 are known to be impacted by leap second.
Cisco Nexus 1000v
VSM module of Cisco Nexus 1000v is known to be impacted by leap second.
Cisco Nexus 5000/5500
Cisco Nexus 5010, 5020 and 5500 switches running NX-OS 5.0, 5.1 or 5.2 are known to be impacted by leap second. Nexus 5010 and 5020 switches are commonly used as NetApp cluster interconnect switches and these devices are most likely to be running affected NX-OS version!
Gen4 and Gen4S models of EMC Avamar are impacted by leap second. EMC has not released publicly available bulleting on the issue but fix will be provided to Avamar customers by EMC support by 30th of June.
Fix is described in Novell KB https://www.novell.com/support/kb/doc.php?id=7016150
EMC VPLEX is impacted by leap second, fix is available and will be implemented by EMC support prior 30th of June.
NetApp DataONTAP is not impacted by leap second.
Tintri VMstore storage appliances are not impacted by leap second. There is no public bulletin regarding this issue but this has been confirmed with Tintri Support.
F5 Networks devices are known not to be impacted by leap second.
Aruba products such as WLAN controllers are known to be impacted by leap second.
Certain versions of Check Point operating systems are impacted by leap second.
Palo Alto Networks
Palo Alto Network devices running PANOS support leap second adjustment.
Juniper devices running JUNOS (M, MX, EX, SRX, etc) support leap second adjustment.