Bug ID 470191: Virtual with FastL4 with loose initiation and close enabled might result in TMM core

Last Modified: Oct 06, 2020

Bug Tracker

Affected Product:  See more info
BIG-IP LTM(all modules)

Known Affected Versions:
11.4.1, 11.5.0, 11.5.1, 11.5.1 HF1, 11.5.1 HF10, 11.5.1 HF11, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.10, 11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4

Fixed In:
12.0.0, 11.6.0 HF5, 11.5.2

Opened: Jul 02, 2014
Severity: 2-Critical
Related AskF5 Article:


Virtual with FastL4, loose initiation and loose close enabled might result in TMM core.


Traffic disrupted while tmm restarts.


The problem can occur when the following conditions are met: - Virtual server with FastL4 profile. - FastL4 profile has loose initiation and loose close enabled. - TCP FIN is received that is not associated with an existing connection.


Do not enable loose initiation and loose close on FastL4 profile

Fix Information

FastL4 component now validates existence of connection peer upon reception of TCP FIN.

Behavior Change