Bug ID 536563: Incoming SYNs that match an existing connection may complete the handshake but will be RST with the cause of 'TCP 3WHS rejected' or 'No flow found for ACK' on subsequent packets.

Last Modified: Oct 16, 2023

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

Known Affected Versions:
10.2.4, 11.0.0, 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, 11.5.1 HF1, 11.6.1 HF1, 11.5.1 HF2, 11.6.1 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, 11.5.1 HF10, 11.5.1 HF11, 11.5.2 HF1, 11.6.2 HF1, 11.5.3 HF1, 11.5.3 HF2, 11.5.4 HF1, 11.5.4 HF2, 11.5.4 HF3, 11.5.4 HF4, 11.1.0, 11.2.0, 11.2.1, 11.3.0, 11.4.0, 11.4.1, 11.5.0, 11.5.1, 11.5.2, 11.5.3, 11.5.4, 11.6.0, 11.6.1, 11.6.2, 12.0.0, 12.0.0 HF1, 12.1.0 HF1, 12.0.0 HF2, 12.1.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.1 HF1, 12.1.1 HF2, 12.1.2 HF1, 12.1.2 HF2, 12.1.0, 12.1.1, 12.1.2

Fixed In:
13.0.0, 12.1.3, 11.6.3, 11.5.5

Opened: Jul 30, 2015

Severity: 3-Major

Symptoms

Incoming SYNs that match an existing connection may complete the handshake but will be RST with the cause of 'TCP 3WHS rejected' on subsequent packets.

Impact

Unexpected RSTs (Clientside).

Conditions

This occurs when the existing connection is closing while waiting on an ACK to the last FIN.

Workaround

None.

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips