On BIG-IP 11.5.1-11.5.4, 11.6.1, and 12.1.0, a virtual server configured with a Client SSL profile may be vulnerable to a chosen ciphertext attack against CBC ciphers. When exploited, this may result in plaintext recovery of encrypted messages through a man-in-the-middle (MITM) attack, despite the attacker not having gained access to the server's private key itself. (CVE-2019-6593 also known as Zombie POODLE and GOLDENDOODLE.)

References

• https://nvd.nist.gov/vuln/detail/CVE-2019-6593
• https://support.f5.com/csp/article/K10065173