BugZero | F5 BugID 826601 - Prevent receive window shrinkage for looped flows ...

F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

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 cores.

Impact

Traffic disrupted while tmm restarts.

Conditions

-- VIP to VIP (looped flow) configuration. -- SYN cookie is used. -- Initial receive window is greater than 3.

Workaround

-- Set the initial receive window value of the VIP to 3.

Fix Information

Receive window shrinkage is prevented for looped flows using SYN cookies.

Change history

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F5 Integration

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F5 Integration

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BugZero Plan

Streamline upgrades with automated vendor bug scrubs

BugZero Plan

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BugZero Prevent

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BugZero Prevent

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F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

Last updated on July 18th, 2026

BugZero Risk Score
8.4 High

Bug Details

Symptoms

Impact

Conditions

Workaround

Fix Information

Links

Top F5 Defects

Ready to prevent the next vendor outage?

F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

Last updated on July 18th, 2026

BugZero Risk Score
8.4 High

Bug Details

Symptoms

Impact

Conditions

Workaround

Fix Information

Links

Top F5 Defects

Ready to prevent the next vendor outage?

F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

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: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

F5 - Defect ID: 826601

Prevent receive window shrinkage for looped flows that use a SYN cookie

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