ESP-IDF is the Espressif Internet of Things (IOT) Development Framework. From 5.2.0 until 5.2.8, 5.3.6, 5.4.5, 5.5.5, and 6.0.3, the OpenThread Border Router Neighbor Discovery packet handler trusts an attacker-controlled ICMPv6 option length while copying into a fixed stack buffer. A host on the same infrastructure link as the Border Router can send a crafted ICMPv6 Router Advertisement to its infrastructure interface whose oversized length causes an out-of-bounds write into adjacent stack memory. Firmware is affected only when CONFIG_OPENTHREAD_BORDER_ROUTER=y; Thread end devices, routers, and RCP firmware without the Border Router feature are unaffected. Exploitation requires no authentication or user interaction and can crash or reboot the device or corrupt adjacent stack state. This issue is fixed in versions 5.2.8, 5.3.6, 5.5.5, and 6.0.3 and is scheduled to be fixed in version 5.4.5.