Bug ID 760550: Retransmitted TCP packet has FIN bit set

Last Modified: Oct 07, 2023

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
11.6.3,,,,, 11.6.4, 11.6.5, 12.1.3,,,,,,,, 12.1.4,, 13.1.1,,,,, 14.0.0,,,,,, 14.0.1, 14.1.0,,,,

Fixed In:
15.1.0, 15.0.0,,, 13.1.3, 12.1.5,

Opened: Mar 06, 2019

Severity: 3-Major


After TCP sends a packet with FIN, retransmitted data earlier in the sequence space might also have the FIN bit set.


The retransmitted packet has the FIN bit set even if it does not contain the end of the data stream. This might cause the connection to stall near the end.


-- Nagle is enabled. -- TCP has already sent a FIN. -- A packet is retransmitted with less than MSS bytes in the send queue.


Set Nagle to disabled in the TCP profile.

Fix Information

The incorrect FIN bit is removed.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips