Last Modified: Aug 19, 2026
Affected Product(s):
BIG-IP LTM
Known Affected Versions:
12.0.0, 12.0.0 hf1, 12.0.0 hf2, 12.0.0 hf3, 12.0.0 hf4, 12.1.0, 12.1.0 hf1, 12.1.0 hf2, 12.1.1, 12.1.1 hf1, 12.1.1 hf2, 12.1.2, 12.1.2 hf1, 12.1.2 hf2, 12.1.3, 12.1.3.1, 12.1.3.2, 12.1.3.3, 12.1.3.4, 12.1.3.5
Fixed In:
13.0.0, 12.1.3.6
Opened: Oct 25, 2016 Severity: 3-Major
BIG-IP does not send the data until receiving the first client ACK.
Delayed completion of the connection.
TCP Fast Open requests an object of less than 1 MSS in size. Fast open and delayed acks enabled.
Disable delayed acks.
TCP sends SYN/ACK immediately after receiving the SYN, and the response as soon as it arrives from the server.