four bytes (nxd_tftp_server.c:1037) and nothing anywhere checks an upper bound, in particular not
against the protocol maximum of 4 + NX_TFTP_FILE_TRANSFER_MAX. Two things follow from that one
missing check, both reachable before any authentication because TFTP has none.
The handler passes `nx_packet_length - 4` straight to FileX:
```c
/* addons/tftp/nxd_tftp_server.c:1863, 1889 */
status = nx_packet_copy(packet_ptr, &temp_ptr,
server_ptr -> nx_tftp_server_packet_pool_ptr, NX_WAIT_FOREVER);
...
fx_file_write(&(client_request_ptr -> nx_tftp_client_request_file),
packet_ptr -> nx_packet_prepend_ptr + 4,
packet_ptr -> nx_packet_length - 4);
```
`nx_packet_length` is the length of a chain, not of one contiguous buffer, so FileX copies past the
end of the first packet:
```
ERROR: AddressSanitizer: heap-buffer-overflow
READ of size 1280 at 0x621000001108 thread T5
#0 __interceptor_memcpy
#1 _fx_utility_memory_copy filex/common/src/fx_utility_memory_copy.c:78
0x621000001108 is 0 bytes to the right of 4104-byte region
```
Those bytes are written into the file the attacker is uploading, and a TFTP read request hands them
back, so this is a memory disclosure with a convenient retrieval channel.
The same datagram also wedges the server. `nx_packet_copy` at :1863 needs
ceil(nx_packet_length / pool_payload) packets and asks for them with NX_WAIT_FOREVER, so when the
attacker sizes the datagram beyond what the pool holds, the server thread suspends and never
returns. A liveness probe after one such datagram times out with the pool at 0 of 12 packets and
the server thread suspended, and no later client is served.
Reject `nx_packet_length > 4 + NX_TFTP_FILE_TRANSFER_MAX` in the DATA branch before either call,
and use a bounded wait rather than NX_WAIT_FOREVER for the copy.
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Eclipse Foundation | NetX Duo | unaffected |
|
No data.
No data.
No data available yet.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
Sign in to view the affected projects.
No advisories yet.
Tue, 29 Sep 2026 18:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | The TFTP server accepts a DATA datagram of any size. The dispatcher rejects datagrams shorter than four bytes (nxd_tftp_server.c:1037) and nothing anywhere checks an upper bound, in particular not against the protocol maximum of 4 + NX_TFTP_FILE_TRANSFER_MAX. Two things follow from that one missing check, both reachable before any authentication because TFTP has none. The handler passes `nx_packet_length - 4` straight to FileX: ```c /* addons/tftp/nxd_tftp_server.c:1863, 1889 */ status = nx_packet_copy(packet_ptr, &temp_ptr, server_ptr -> nx_tftp_server_packet_pool_ptr, NX_WAIT_FOREVER); ... fx_file_write(&(client_request_ptr -> nx_tftp_client_request_file), packet_ptr -> nx_packet_prepend_ptr + 4, packet_ptr -> nx_packet_length - 4); ``` `nx_packet_length` is the length of a chain, not of one contiguous buffer, so FileX copies past the end of the first packet: ``` ERROR: AddressSanitizer: heap-buffer-overflow READ of size 1280 at 0x621000001108 thread T5 #0 __interceptor_memcpy #1 _fx_utility_memory_copy filex/common/src/fx_utility_memory_copy.c:78 0x621000001108 is 0 bytes to the right of 4104-byte region ``` Those bytes are written into the file the attacker is uploading, and a TFTP read request hands them back, so this is a memory disclosure with a convenient retrieval channel. The same datagram also wedges the server. `nx_packet_copy` at :1863 needs ceil(nx_packet_length / pool_payload) packets and asks for them with NX_WAIT_FOREVER, so when the attacker sizes the datagram beyond what the pool holds, the server thread suspends and never returns. A liveness probe after one such datagram times out with the pool at 0 of 12 packets and the server thread suspended, and no later client is served. Reject `nx_packet_length > 4 + NX_TFTP_FILE_TRANSFER_MAX` in the DATA branch before either call, and use a bounded wait rather than NX_WAIT_FOREVER for the copy. | |
| Weaknesses | CWE-125 CWE-770 |
|
| References |
| |
| Metrics |
cvssV4_0
|
Subscriptions
No data.
MITRE
Status: PUBLISHED
Assigner: eclipse
Published:
Updated: 2026-09-29T18:44:38.207Z
Reserved: 2026-09-29T16:15:09.632Z
Link: CVE-2026-102713
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-29T18:17:10.457
Modified: 2026-09-29T18:17:10.457
Link: CVE-2026-102713
Redhat
No data.
OpenCVE Enrichment
No data.