RIOT OS Stack-Based Buffer Overflow Vulnerability in Ethos Utility

A stack-based buffer overflow vulnerability has been identified in RIOT OS versions through 2026.01-devel-317. This vulnerability arises in the ethos utility, specifically within the _handle_char() function, where incoming serial frame data is processed. The issue is caused by inadequate bounds checking, allowing incoming bytes to be appended to a fixed-size stack buffer without verifying that the write index remains within safe limits. An attacker can exploit this by sending crafted serial or TCP-framed input, causing the write index to exceed the buffer size and leading to memory corruption and application crashes. Under certain conditions, this vulnerability could also allow arbitrary code execution, depending on compiler options and runtime protections.

Impact

Exploitation of this vulnerability causes a stack-based buffer overflow, leading to memory corruption and application crashes. However, according to the vulnerability disclosure, this issue could potentially be exploited for arbitrary code execution, depending on specific compiler options and runtime protections.

Reproduction

The vulnerability can be reproduced by running the RIOT OS ethos utility and sending a payload of crafted serial or TCP-framed input that exceeds the buffer size of the stack buffer used in the _handle_char() function. This can be done using a Python script that acts as a malicious server, sending the payload when the ethos client connects.