Bug ID 612694: TCP::close with no pool member results in zombie flows

Last Modified: Aug 19, 2026

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

Known Affected Versions:
11.6.0, 11.6.0 hf1, 11.6.0 hf2, 11.6.0 hf3, 11.6.0 hf4, 11.6.0 hf5, 11.6.0 hf6, 11.6.0 hf7, 11.6.0 hf8, 11.6.1, 11.6.1 hf1, 11.6.1 hf2, 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, 12.1.3.6, 12.1.3.7, 12.1.4, 12.1.4.1, 12.1.5, 12.1.5.1, 12.1.5.2, 12.1.5.3, 12.1.6

Fixed In:
13.0.0, 11.6.2

Opened: Aug 25, 2016

Severity: 3-Major

Related Article: K70557109

Symptoms

'tmsh show sys conn all-properties' shows connections whose idle time exceeds the timeout.

Impact

Connection does not tear itself down.

Conditions

There is no pool member, and a TCP::close iRule activates (typically after a TCP::respond).

Workaround

Make TCP::close conditional on pool failure, and rely on the pool failure to RST the connection rather than perform a clean TCP close.

Fix Information

The system now properly handles TCP teardown when TCP::close has already torn down the rest of the stack.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips