# CVE-2026-102761: Eclipse NetX Duo WebSocket client memory corruption in packet unmasking

Source: https://junglewise.ai/threats/cve-2026-102761-netx-duo-s-websocket-client-resets-the-unmasking-cursor-to-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-29. Updated: 2026-09-29  
License: CC BY 4.0 with a link back

CVE-2026-102761 · Severity: info · Published 2026-09-29

Eclipse NetX Duo is an embedded TCP/IP networking stack used in IoT and embedded systems. A vulnerability in the WebSocket client allows an attacker to corrupt memory in the network packet control structures by sending a crafted masked WebSocket frame split across multiple packets. An attacker positioned to intercept or control the WebSocket server could write attacker-chosen data to arbitrary locations in heap memory.

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

## Quick answers

**Is CVE-2026-102761 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-102761 being exploited in the wild.

**How severe is CVE-2026-102761?** Informational severity, published 29 September 2026.

**Which products and versions are affected?** Eclipse NetX Duo <UNKNOWN>.

**Is there a fix for CVE-2026-102761?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-102761 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-102761?** Check whether you run Eclipse 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.

## Technical details

The WebSocket client's unmasking loop incorrectly resets the XOR cursor to the first packet in a chain each time it advances to the next packet, while the loop bounds remain tied to the current packet. This causes the XOR operation to write past the current packet's payload and into adjacent control structures. The attacker controls the content written via the four-byte WebSocket masking key, enabling targeted heap corruption.

## Affected products

- Eclipse NetX Duo <UNKNOWN>

## Timeline

- 2026-09-29: disclosed

## References

- [https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-6xgx-v7gw-qjph](https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-6xgx-v7gw-qjph)

## Related threats

- [Eclipse NetX Duo NetX Secure heap out-of-bounds read in TLS 1.3 Certificate parser](https://junglewise.ai/threats/cve-2026-92843-a-missing-bounds-check-in-the-tls-1-3-certificate-message-parser)
- [Eclipse NetX Duo DTLS parser out-of-bounds read](https://junglewise.ai/threats/cve-2026-102712-on-the-first-dtls-clienthello-the-parser-copies-a-device-claimed)