BugZero | F5 BugID 949145 - Improve TCP's response to partial ACKs during loss...

F5 - Defect ID: 949145

Improve TCP's response to partial ACKs during loss recovery

F5 - Defect ID: 949145

Improve TCP's response to partial ACKs during loss recovery

Last updated on July 18th, 2026

BugZero Risk Score
6.7 Medium

Overall: 6.7

Severity: 7.3

Community: 4.2

Lifecycle: 7.0

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Bug Details

Priority: 3-Major
Status: Verified
Impact Category: Local Traffic Manager

Description

Symptoms

- A bursty retransmission occurs during TCP's loss recovery period.

Impact

The bursty retransmissions may lead to more data getting lost due to large amount of data being injected into the network.

Conditions

- TCP filter is used. - TCP stack is used instead of TCP4 stack (based on profile settings). - Packet loss occurs during the data transfer and TCP's loss recovery takes place.

Workaround

In versions prior to v16.0.0, use a TCP profile which selects the TCP4 stack instead of the TCP stack. There is no workaround for version 16.0.0.

Fix Information

Partial ACK handling during loss recovery is improved.

Change history

Links

Original Vendor Announcement

Relevant Products

Click on a version to see all relevant bugs

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, 11.6.2, 11.6.2 hf1, 11.6.3, 11.6.3.1, 11.6.3.2, 11.6.3.3, 11.6.3.4, 11.6.4, 11.6.5, 11.6.5.1, 11.6.5.2, 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, 13.1.0, 13.1.0.1, 13.1.0.2, 13.1.0.3, 13.1.0.4, 13.1.0.5, 13.1.0.6, 13.1.0.7, 13.1.0.8, 13.1.1, 13.1.1.2, 13.1.1.3, 13.1.1.4, 13.1.1.5, 13.1.3, 13.1.3.1, 13.1.3.2, 13.1.3.3, 13.1.3.4, 13.1.3.5, 14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.5, 14.1.0.6, 14.1.2, 14.1.2.1, 14.1.2.2, 14.1.2.3, 14.1.2.4, 14.1.2.5, 14.1.2.6, 14.1.2.7, 14.1.2.8, 14.1.3, 15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 15.1.1, 16.0.0, 16.0.0.1, 16.0.1

Fixed versions: 16.1.0, 16.0.1.1, 15.1.2, 14.1.3.1, 13.1.3.6, 12.1.5.3, 11.6.5.3

Relevant Products

Click on a version to see all relevant bugs

Fixed versions: 16.1.0, 16.0.1.1, 15.1.2, 14.1.3.1, 13.1.3.6, 12.1.5.3, 11.6.5.3

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F5 Integration

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BugZero Plan

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F5 - Defect ID: 949145

Improve TCP's response to partial ACKs during loss recovery

F5 - Defect ID: 949145

Improve TCP's response to partial ACKs during loss recovery

Last updated on July 18th, 2026

BugZero Risk Score6.7 Medium

Bug Details

Symptoms

Impact

Conditions

Workaround

Fix Information

Links

Top F5 Defects

Ready to prevent the next vendor outage?

F5 - Defect ID: 949145

Improve TCP's response to partial ACKs during loss recovery

F5 - Defect ID: 949145

Improve TCP's response to partial ACKs during loss recovery

Last updated on July 18th, 2026

BugZero Risk Score6.7 Medium

Bug Details

Symptoms

Impact

Conditions

Workaround

Fix Information

Links

Top F5 Defects

Ready to prevent the next vendor outage?

BugZero Risk Score
6.7 Medium

BugZero Risk Score
6.7 Medium