# CVE-2026-102721: Memory corruption in NetX Duo

> A malicious TFTP server can trigger a heap buffer overflow in the NetX Duo client, leaking adjacent memory or causing a crash.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Sep 2026
- **Updated:** 29 Sep 2026
- **Also known as:** GHSA-5cxq-44w6-64mx, GHSA-wvc9-5m9h-rvxc

## What is CVE-2026-102721?

CVE-2026-102721 is a medium-severity memory corruption vulnerability in Eclipse Foundation NetX Duo, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-102721?


## How do I fix CVE-2026-102721?

No fix has been published for CVE-2026-102721 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-102721 being exploited?

There is no known exploitation of CVE-2026-102721 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102721 and fix it if it is affected.

What it is: CVE-2026-102721 is a medium-severity memory corruption vulnerability in Eclipse Foundation NetX Duo, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-102721 in the wild and no public exploit code.

Affected product: Eclipse Foundation NetX Duo. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-102721/ (Markdown: https://insights.sbomify.com/CVE-2026-102721/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102721
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102721
- OSV: https://osv.dev/vulnerability/CVE-2026-102721

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102721/
Summaries are generated and may contain mistakes; the official description above is the record.