BugZero | F5 BugID 1818861 - Timestamp cookies are not compatible with fastl4 m...

F5 - Defect ID: 1818861

Timestamp cookies are not compatible with fastl4 mirroring.

F5 - Defect ID: 1818861

Timestamp cookies are not compatible with fastl4 mirroring.

Last updated on July 30th, 2026

BugZero Risk Score
6.7 Medium

Overall: 6.7

Severity: 7.3

Community: 4.2

Lifecycle: 7.0

What is the BugZero Risk Score?

F5 Integration

Learn more about where this data comes from

F5 Integration

Learn more

BugZero Plan

Streamline upgrades with automated vendor bug scrubs

BugZero Plan

Learn more

BugZero Prevent

Wish you caught this bug sooner? Get proactive today.

BugZero Prevent

Learn more

Bug Details

Priority: 3-Major
Status: Verified
Impact Category: Advanced Firewall Manager

Description

Symptoms

DOS tcp-ack-ts vector with tscookies option enabled is not compatible with fastl4 (L4) mirroring.

Impact

Existing connections hang due to tsval not being transformed properly on a newly active device.

Conditions

- DOS tcp-ack-ts vector with tscookies option enabled - Mirroring configured on fastL4 TCP virtual. - FastL4 profile with timestamp 'preserve' option configured.

Workaround

Set fastl4 timestamp option to strip/rewrite.

Fix Information

None

Change history

Links

Original Vendor Announcement

Relevant Products

Click on a version to see all relevant bugs

Affected versions:16.1.0, 16.1.1, 16.1.2, 16.1.2.1, 16.1.2.2, 16.1.3, 16.1.3.1, 16.1.3.2, 16.1.3.3, 16.1.3.4, 16.1.3.5, 16.1.4, 16.1.4.1, 16.1.4.2, 16.1.4.3, 16.1.5, 16.1.5.1, 16.1.5.2, 16.1.6, 16.1.6.1, 17.1.0, 17.1.0.1, 17.1.0.2, 17.1.0.3, 17.1.1, 17.1.1.1, 17.1.1.2, 17.1.1.3, 17.1.1.4, 17.1.2, 17.1.2.1, 17.1.2.2, 17.1.3, 17.1.3.1, 17.1.3.2, 17.1.3.4, 17.5.0, 17.5.1, 17.5.1.2, 17.5.1.3, 17.5.1.4, 17.5.1.5, 17.5.1.6, 17.5.1.8

Fixed versions: No known fixed versions

Relevant Products

Click on a version to see all relevant bugs

Fixed versions: No known fixed versions

Top F5 Defects

9.6Defect ID: 546260
TMM can crash if using the v6rd profile
9.6Defect ID: 934133
Unable to Create/delete ltm virtual server via CLI transaction when destination is not specified on the ltm virtual object
9.6Defect ID: 1154417
Profile based attack is not mitigated at hardware on L2 wire setup
9.6Defect ID: 913713
Rebooting a blade causes MCPd to core as it rejoins the cluster
9.6Defect ID: 2141125
Multicast traffic is dropped with incorrect VLAN tagging

F5 Integration

Learn more about where this data comes from

F5 Integration

Learn more

BugZero Plan

Streamline upgrades with automated vendor bug scrubs

BugZero Plan

Learn more

BugZero Prevent

Wish you caught this bug sooner? Get proactive today.

BugZero Prevent

Learn more

Ready to prevent the next vendor outage?

Get a demo

F5 - Defect ID: 1818861

Timestamp cookies are not compatible with fastl4 mirroring.

F5 - Defect ID: 1818861

Timestamp cookies are not compatible with fastl4 mirroring.

Last updated on July 30th, 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: 1818861

Timestamp cookies are not compatible with fastl4 mirroring.

F5 - Defect ID: 1818861

Timestamp cookies are not compatible with fastl4 mirroring.

Last updated on July 30th, 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