Last Modified: Sep 05, 2026
Affected Product(s):
BIG-IP APM
Known Affected Versions:
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, 17.5.1, 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 In:
17.5.1.9, 17.1.3.5
Opened: Dec 09, 2025 Severity: 3-Major
On BIG-IP APM systems, a crash of the Traffic Management Microkernel (TMM) may happen when a client device sends an unexpected extra trailing carriage return or line feed (CR/LF) during an iSession tunnel reconnection. This issue has been observed in a specific user scenario involving a certain client device. In this case, the Edge Client installation was a hybrid of multiple versions, which resulted in the transmission of these unexpected CR/LF characters following the iSession request
-- Traffic is disrupted while the TMM restarts -- Disruption of user sessions -- The issue is highly specific to certain client configurations and is not expected to be widespread
- iSession tunnels in use - Client device sends an extra CR/LF after the iSession request, often due to a hybrid or corrupted Edge Client installation
None
- The fix addresses the scenario where the HTTP filter does not unpause ingress when moving to passthrough mode, and iSession/VPN filters may mishandle unexpected CR/LF data. - The fix ensures that extra CR/LF data does not cause the TMM to crash during iSession reconnects. - Engineering Hotfixes (EHF) are availble for 17.1.3 (including rollup with EHF 0.20.11)