BugZero | F5 BugID 625198 - TMM might crash when TCP DSACK is enabled

F5 - Defect ID: 625198

TMM might crash when TCP DSACK is enabled

F5 - Defect ID: 625198

TMM might crash when TCP DSACK is enabled

Last updated on July 18th, 2026

BugZero Risk Score
8.4 High

Overall: 8.4

Severity: 9.1

Community: 4.2

Lifecycle: 7.0

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Bug Details

Priority: 2-Critical
Status: Verified
Impact Category: Local Traffic Manager

Description

Symptoms

TMM crashes

Impact

Traffic disrupted while tmm restarts.

Conditions

All of the below are required to see this behavior: DSACK is enabled MPTCP, rate-pace, tail-loss-probe, and fast-open are disabled. cmetrics-cache-timeout is set to zero; congestion control is high-speed, new-reno, reno, or scalable; AND Nagle is not set to 'auto'. an iRule exists that changes any of the conditions above besides DSACK. various client packet combinations interact in certain ways with the iRule logic.

Workaround

Change any of the conditions above.

Fix Information

TCP maintains state appropriately to avoid crash.

Change history

Links

Original Vendor Announcement

Relevant Products

Click on a version to see all relevant bugs

Affected versions:11.5.1, 11.5.1 hf1, 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, 11.5.1 hf10, 11.5.1 hf11, 11.5.2, 11.5.2 hf1, 11.5.3, 11.5.3 hf1, 11.5.3 hf2, 11.5.4, 11.5.4 hf1, 11.5.4 hf2, 11.5.4 hf3, 11.5.4 hf4, 11.5.5, 11.5.6, 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 versions: 13.0.0, 11.6.2, 11.5.7

Relevant Products

Click on a version to see all relevant bugs

Fixed versions: 13.0.0, 11.6.2, 11.5.7

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F5 - Defect ID: 625198

TMM might crash when TCP DSACK is enabled

F5 - Defect ID: 625198

TMM might crash when TCP DSACK is enabled

Last updated on July 18th, 2026

BugZero Risk Score8.4 High

Bug Details

Symptoms

Impact

Conditions

Workaround

Fix Information

Links

Top F5 Defects

Ready to prevent the next vendor outage?

F5 - Defect ID: 625198

TMM might crash when TCP DSACK is enabled

F5 - Defect ID: 625198

TMM might crash when TCP DSACK is enabled

Last updated on July 18th, 2026

BugZero Risk Score8.4 High

Bug Details

Symptoms

Impact

Conditions

Workaround

Fix Information

Links

Top F5 Defects

Ready to prevent the next vendor outage?

BugZero Risk Score
8.4 High

BugZero Risk Score
8.4 High