Last Modified: Sep 16, 2026
Affected Product(s):
BIG-IP MA-All
Known Affected Versions:
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, 17.1.3.5, 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, 17.5.1.9, 21.0.0, 21.0.0.1, 21.0.0.2, 21.0.0.3
Opened: Feb 10, 2026 Severity: 2-Critical
The eth2 interface in a f5os tenant is used for communications between the tenant and the F5OS host, and is assigned an IP address, using DHCP, from the F5OS host. When the DHCP lease expires after 999 days, the management interface (eth0 or mgmt) IP address is incorrectly changed to eth2's IP address (100.69.x.x/24), causing loss of remote management access. This can occur when the DHCP lease renewal occurs after 999 days, or when executing a manual command to renew eth2's DHCP lease (dhclient -r). Logs similar to the following can be seen from the tenant's /var/log/boot.log: info dhcp_config[20430]: management_ip = 100.69.1.1 info dhcp_config[20430]: F5::COAPI::TransactionalSave Succeeded. info dhcp_config[20430]: domain_search = <default.svc.cluster.local. svc.cluster.local. cluster.local. chassis.local.> info dhcp_config[20430]: domain_name = <default.svc.cluster.local> info dhcp_config[20430]: In update_ltcfg_field(). info dhcp_config[20430]: LTCFG Field => ('dns', 'search', 'dns') info dhcp_config[20430]: New value => 'default.svc.cluster.local.,svc.cluster.local.,cluster.local.,chassis.local.' info dhcp_config[20430]: Existing value => 'localhost' info dhcp_config[20430]: dns_servers = <10.10.1.10> info dhcp_config[20430]: In update_ltcfg_field(). info dhcp_config[20430]: LTCFG Field => ('dns', 'nameservers', 'dns') info dhcp_config[20430]: New value => '10.10.1.10' info dhcp_config[20430]: Existing value => '10.10.1.241,10.10.1.242,10.10.1.243' info dhcp_config[20430]: In update_ltcfg_config_source() for 'dns'. info dhcp_config[20430]: New 'config_source' value => '0' info dhcp_config[20430]: Existing value => '0' info dhcp_config[20430]: No change in 'config_source' for 'dns'. Skip update. info dhcp_config[20430]: In update_ltcfg_field(). info dhcp_config[20430]: LTCFG Field => ('dns', 'description', 'dns') info dhcp_config[20430]: New value => 'configured-by-dhcp' info dhcp_config[20430]: Existing value => '' info dhcp_config[20430]: F5::COAPI::TransactionalSave Succeeded. info dhcp_config[20430]: hostname = 'bigip1.default.svc.cluster.local' info dhcp_config[20430]: In update_ltcfg_field(). info dhcp_config[20430]: LTCFG Field => ('system', 'hostname', 'system') info dhcp_config[20430]: New value => 'bigip1.default.svc.cluster.local' info dhcp_config[20430]: Existing value => 'bigip1.default.svc.cluster.local' info dhcp_config[20430]: No change in ltcfg field 'hostname'. Skip update. info dhcp_config[20430]: Successfully finished the execution of /usr/libexec/dhcp-config. Notice that in addition to changing the management IP address it also changes the DNS and hostname.
Loss of remote connectivity to management interface.
- An F5OS rSeries tenant has been running for 999 days and its DHCP-enabled eth2 interface renews the lease. - This may also occur if an administrator manually executes a command that forces eth2 to renew its lease.
Reboot the affected BIG-IP tenant or change tenant state from "deployed" to "configured" and back to "deployed" via F5OS host. DNS and hostname settings may also need to be changed back to their previous value.
None