# CVE-2026-94018: Eclipse ThreadX NetX Duo Web HTTP server use-after-free

Source: https://junglewise.ai/threats/cve-2026-94018-the-web-add-on-s-http-server-dereferences-and-releases-an  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-94018 · Severity: info · Published 2026-10-20

Eclipse ThreadX NetX Duo is a network stack and add-on library for embedded systems that includes an HTTP server for serving web content. An attacker sending a malformed PUT request with a manipulated Content-Length header can trigger a use-after-free vulnerability in the HTTP server, potentially causing the application to crash or, in certain configurations, corrupting internal memory structures that could lead to arbitrary code execution.

Technologies: [Eclipse ThreadX NetX Duo](https://junglewise.ai/threats/technologies/eclipse-threadx-netx-duo). Vendors: [Eclipse ThreadX](https://junglewise.ai/threats/vendors/eclipse-threadx).

## Quick answers

**Is CVE-2026-94018 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-94018 being exploited in the wild.

**How severe is CVE-2026-94018?** Informational severity, published 20 October 2026.

**Which products and versions are affected?** Eclipse ThreadX NetX Duo 6.4.2 through 6.5.1.202602.

**Is there a fix for CVE-2026-94018?** Yes: fixed in NetX Duo 6.5.2.202603. Until then: Do not serve PUT requests, or require authentication for PUT requests. Ensure error checking is enabled (NX_DISABLE_ERROR_CHECKING not defined) to reduce impact to denial of service rather than packet pool corruption. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-94018 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-94018?** Check whether you run Eclipse ThreadX NetX Duo at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in NetX Duo 6.5.2.202603

Do not serve PUT requests, or require authentication for PUT requests. Ensure error checking is enabled (NX_DISABLE_ERROR_CHECKING not defined) to reduce impact to denial of service rather than packet pool corruption.

## Technical details

An uninitialized pointer in the PUT request handler is dereferenced and released when a Content-Length underflow is detected, occurring when delivered body bytes exceed the announced Content-Length and cause a ULONG wraparound. The vulnerability is reachable by an unauthenticated remote client via a single malformed PUT request. In default builds with error checking enabled, this typically results in a crash; in builds with NX_DISABLE_ERROR_CHECKING, the corrupted pointer can be linked into the packet pool's free list, corrupting allocations.

## Affected products

- Eclipse ThreadX NetX Duo 6.4.2 through 6.5.1.202602

## Timeline

- 2026-10-02: disclosed
- 2026-03: patched: Fixed in version 6.5.2.202603

## References

- [https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-wjxf-gjm5-jh5q](https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-wjxf-gjm5-jh5q)

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- [Eclipse ThreadX NetX Duo HTTP server request framing confusion](https://junglewise.ai/threats/cve-2026-93003-the-web-add-on-s-http-server-searches-the-entire-request-packet)
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