Bug ID 665732: FastHTTP may crash when receiving a fragmented IP packet

Last Modified: Aug 19, 2026

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

Known Affected Versions:
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, 11.5.7, 11.5.8, 11.5.9, 11.5.10, 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, 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, 13.0.0, 13.0.0 hf1, 13.0.0 hf2, 13.0.0 hf3, 13.0.1

Fixed In:
13.1.0, 12.1.3.2, 11.6.4

Opened: May 19, 2017

Severity: 2-Critical

Related Article: K45001711

Symptoms

A virtual server configured to use FastHTTP may cause a TMM core if fragmented IP packets are received by the virtual. This can be observed by the following TMM log statement: panic: Assertion 'l4hdr set' failed.

Impact

Intermittent TMM core, resulting in a TMM restart. Traffic disrupted while tmm restarts.

Conditions

A virtual server configured with a FastHTTP profile receiving fragmented IP packets.

Workaround

Use a different profile than FastHTTP, such as a full proxy with TCP/HTTP filters.

Fix Information

Force packet reassembly before packet is forwarded to a FastHTTP virtual.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips