CVE-2026-109439 (CVSS 4.0 9.3, CWE-306) affects Lantronix XPress-DR and XPress-DR-I (CoBos-family) firmware through 8.1.0.0. The unauthenticated UDP configuration protocol on port 30718 (0x77FE) accepts a type 0xF8 query to read live configuration and a type 0xFD frame with exactly 0x78 body bytes to persistently rewrite device IP and serial-channel forwarding records to EEPROM across reboots. The XPress-DR line reached end-of-life/end-of-support in February 2025, so replace exposed units. Until then, disable UDP/30718 via the device Security option that turns off port 77FEh, or block the port at the network boundary. Credit: D6fault. Not on CISA KEV as of catalogVersion 2026.10.14.