Executive brief
nanoMODBUS is a software library used by embedded devices and microcontrollers to communicate over industrial networks. A flaw in how it handles incoming network messages allows an attacker to crash the device or potentially read and write unauthorized data. This could lead to equipment downtime or the manipulation of industrial control processes.
Technical details
An off-by-one buffer overflow exists in the recv_msg_header() function of the nanoMODBUS Modbus/TCP server. By sending a specially crafted MBAP frame with the Length field set to 255, a remote unauthenticated attacker can write one byte past the end of the 260-byte receive buffer. This overflow corrupts the adjacent buffer-index field in the library's state structure. On bare-metal or RTOS targets lacking memory protection, this can lead to a denial of service via invalid memory access, one-byte information disclosure, or unauthorized writes to register addresses during Write Multiple Registers (FC16) operations.
Affected products
- debevv nanoMODBUS through v1.23.0
Timeline
- 2026-06-14: advisory: NVD publication date