Last Modified: Feb 05, 2026
Affected Product(s):
BIG-IP TMOS
Known Affected Versions:
17.1.1.4, 17.1.2, 17.1.2.1, 17.1.2.2, 17.1.3, 17.1.3.1, 17.5.1.4, 21.0.0, 21.0.0.1
Opened: Feb 04, 2026 Severity: 3-Major
Tmm crashes when an iRule command is triggered.
Traffic disrupted while tmm restarts.
1. An iRule invokes HSL::send on an undefined variable and which reference an HSL pool 2. Syslog messages are configured to be sent to the same HSL pool, which causes a log recursion to occur on the error message # See undefined $hsl ltm rule /Common/c_hsl_rule { when CLIENT_DATA { # Log the raw payload to /var/log/ltm for debugging log local0. "Payload received from [IP::client_addr]:[UDP::client_port] -> [UDP::payload]" # Send the raw payload to the C pool HSL::send $hsl "[UDP::payload]" } } which leads to logging of the error And syslog is redirected to the same pool, thus causing errors generated by the iRule to end up recursing into MDS. sys log-config destination remote-high-speed-log /Common/clog-rhl { pool-name /Common/clog protocol udp } sys log-config destination remote-syslog /Common/clog-rs { remote-high-speed-log /Common/clog-rhl }
Make sure variable is defined. Potentially use a "catch" as well.
None