# CVE-2026-102759: NetX Secure TLS MAC verification bypass in application-data records

Source: https://junglewise.ai/threats/cve-2026-102759-netx-secure-tls-accepts-an-empty-application-data-record-without  
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-2026-102759 · Severity: info · Published 2026-09-29

NetX Secure TLS, used to provide encrypted communication for networked devices, fails to verify the message authentication code (MAC) on empty application-data records. An attacker could craft malicious TLS messages that bypass MAC verification, potentially allowing message tampering or injection attacks on encrypted connections.

Vendors: [Eclipse ThreadX](https://junglewise.ai/threats/vendors/eclipse-threadx).

## Quick answers

**Is CVE-2026-102759 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-102759 being exploited in the wild.

**How severe is CVE-2026-102759?** Informational severity, published 29 September 2026.

**Which products and versions are affected?** Eclipse ThreadX NetX Secure TLS.

**Is there a fix for CVE-2026-102759?** 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-2026-102759 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-102759?** Check whether you run Eclipse ThreadX NetX Secure TLS. 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 `_nx_secure_verify_mac` function in NetX Secure TLS treats a decrypted application record whose length equals the negotiated MAC size as valid without actually generating or comparing the received MAC. This allows empty application-data records to bypass MAC verification by advancing the receive sequence number. While empty records are legal per TLS 1.0 (used as BEAST mitigation), the lack of MAC verification is a cryptographic validation flaw.

## Affected products

- Eclipse ThreadX NetX Secure TLS

## Timeline

- 2026-09-29: disclosed

## References

- [https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-m7j3-vh25-xc8p](https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-m7j3-vh25-xc8p)