The proprietary F5 TLS stack is vulnerable to Ticketbleed. It exposes 31 bytes per request to the attacker and will ultimately invalidate the encryption.
Ticketbleed Security Assessment

CVSS Vector: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Ticketbleed Vulnerability Information
The proprietary F5 TLS stack is vulnerable to Ticketbleed. It exposes 31 bytes per request to the attacker and will ultimately invalidate the encryption.
How to Prevent Ticketbleed
Please refer to the website of the manufacturer for a guide to resolve the issue.