Vulnerability details

An issue was discovered in MBed OS 6.16.0. Its hci parsing software dynamically determines the length of certain hci packets by reading a byte from its header. This value is assumed to be greater than or equal to 3, but the software doesn't ensure that this is the case. Supplying a length less than 3 leads to a buffer overflow in a buffer that is allocated later. It is simultaneously possible to cause another integer overflow by supplying large length values because the provided length value is increased by a few bytes to account for additional information that is supposed to be stored there. This bug is trivial to exploit for a denial of service but is not certain to suffice to bring the system down and can generally not be exploited further because the exploitable buffer is dynamically allocated.

• https://github.com/mbed-ce/mbed-os/blob/54e8693ef4ff7e025018094f290a1d5cf380941f/connectivity/FEATURE_BLE/libraries/cordio_stack/ble-host/sources/hci/dual_chip/hci_evt.c#L2748
• https://github.com/mbed-ce/mbed-os/pull/386