Eclipse NetX Duo up to 6.5.1 TFTP Client nxd_tftp_client.c _nxd_tftp_client_file_read heap-based overflow

Summaryinfo

A vulnerability was found in Eclipse NetX Duo up to 6.5.1. It has been declared as critical. The affected element is the function _nxd_tftp_client_file_read of the file addons/tftp/nxd_tftp_client.c of the component TFTP Client. The manipulation results in heap-based overflow. This vulnerability was named CVE-2026-102721. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability was found in Eclipse NetX Duo up to 6.5.1. It has been classified as critical. Affected is the function _nxd_tftp_client_file_read of the file addons/tftp/nxd_tftp_client.c of the component TFTP Client. The manipulation with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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: ```c /* 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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-102721 since 09/29/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/29/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• Eclipse

Name

• NetX Duo

Version

• 6.5.0
• 6.5.1

License

• open-source

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