CVE-2026-102721

In Eclipse ThreadX NetX Duo versions 6.0 through 6.5.2.202603a, the TFTP client copies the message of a received ERROR packet without bounding the copy by the end of the datagram, and the TFTP server reads one byte past a minimal ERROR packet. A malicious TFTP server can make the client copy up to 64 bytes of adjacent packet-pool memory into the error string the application retrieves, or fault on targets with memory protection.

In Eclipse ThreadX NetX Duo versions 6.0 through 6.5.2.202603a, the TFTP client copies the message of a received ERROR packet without bounding the copy by the end of the datagram, and the TFTP server reads one byte past a minimal ERROR packet. A malicious TFTP server can make the client copy up to 64 bytes of adjacent packet-pool memory into the error string the application retrieves, or fault on targets with memory protection.

A TFTP server that answers with a short ERROR packet makes the client read up to 64 bytes past the

received datagram.

Each receive path checks only that the datagram is at least four bytes long (nxd_tftp_client.c:1229,

1521, 1984). When the opcode is NX_TFTP_CODE_ERROR the message string is copied with a loop whose

only limits are the destination buffer and a NUL byte:

/* addons/tftp/nxd_tftp_client.c:1769 */



for (i = 0; (i < (sizeof(tftp_client_ptr -> nx_tftp_client_error_string) - 1)) && (*buffer_ptr); i++)

Nothing compares buffer_ptr against nx_packet_append_ptr. An ERROR packet that carries no

terminating NUL, which a server controls completely, walks the loop off the end of the packet until

it happens to meet a zero byte or fills the 64 byte destination.

ERROR: AddressSanitizer: heap-buffer-overflow



READ of size 1 at 0x60d0000000c8 thread T4

    #0 _nxd_tftp_client_file_read  addons/tftp/nxd_tftp_client.c:1769


0x60d0000000c8 is 0 bytes to the right of 136-byte region

The open path has the same loop at :1327 and reports the same way. What is read lands in

nx_tftp_client_error_string, which the application is expected to display or log, so adjacent

packet pool memory ends up in whatever the device does with the error text.

Add (buffer_ptr < packet_ptr -> nx_packet_append_ptr) to the loop condition in all three paths.

In Eclipse ThreadX NetX Duo versions 6.0 through 6.5.2.202603a, the TFTP client copies the message of a received ERROR packet without bounding the copy by the end of the datagram, and the TFTP server reads one byte past a minimal ERROR packet. A malicious TFTP server can make the client copy up to 64 bytes of adjacent packet-pool memory into the error string the application retrieves, or fault on targets with memory protection.

In Eclipse ThreadX NetX Duo versions 6.0 through 6.5.2.202603a, the TFTP client copies the message of a received ERROR packet without bounding the copy by the end of the datagram, and the TFTP server reads one byte past a minimal ERROR packet. A malicious TFTP server can make the client copy up to 64 bytes of adjacent packet-pool memory into the error string the application retrieves, or fault on targets with memory protection.