CVE-2025-55081 is a buffer over-read vulnerability identified in the Eclipse Foundation's NetX Duo library, a component of the ThreadX real-time operating system widely used in embedded and IoT devices. The vulnerability exists in the _nx_secure_tls_process_clienthello() function, which processes the SSL/TLS client hello message during the handshake phase. Specifically, the function fails to verify the length fields for the ciphersuite list and compression methods within the client hello message. An attacker can exploit this by sending a specially crafted client hello message with length values that exceed expected bounds, causing the function to read memory beyond the allocated buffers. This out-of-bounds read can potentially lead to information disclosure or cause the application to behave unpredictably, including crashes. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. The CVSS 4.0 base score is 6.9 (medium severity), reflecting the network attack vector and lack of required privileges but limited impact on confidentiality, integrity, and availability. No patches or known exploits are currently available, but the issue was publicly disclosed on October 15, 2025. The vulnerability affects all versions of NetX Duo prior to 6.4.4, necessitating updates to remediate the flaw. Given NetX Duo's prevalence in embedded systems, this vulnerability could affect a broad range of devices, especially those implementing secure communications via TLS.

For European organizations, the primary impact of CVE-2025-55081 lies in the potential exposure of sensitive memory contents due to out-of-bounds reads during TLS handshakes. This could lead to partial information disclosure, which might include cryptographic material or other sensitive data residing in memory. Additionally, the vulnerability could cause device instability or crashes, impacting availability of critical embedded or IoT systems. Sectors relying heavily on embedded devices with secure communications—such as automotive, industrial control systems, healthcare devices, and telecommunications—may face operational disruptions or increased risk of targeted attacks exploiting this flaw. The lack of authentication and user interaction requirements means attackers can remotely target vulnerable devices over the network, increasing the threat surface. While no known exploits exist yet, the medium severity rating and widespread use of NetX Duo in European-manufactured embedded products underscore the need for vigilance. Failure to address this vulnerability could lead to reputational damage, regulatory scrutiny under GDPR if personal data is exposed, and potential safety risks in critical infrastructure environments.

To mitigate CVE-2025-55081, European organizations should prioritize upgrading all affected NetX Duo instances to version 6.4.4 or later once the patch is released by the Eclipse Foundation. Until patches are available, organizations should implement network-level defenses such as deep packet inspection to detect and block malformed TLS client hello messages with anomalous length fields. Employing strict input validation and anomaly detection on TLS traffic can reduce exposure. For embedded devices where immediate patching is challenging, consider isolating vulnerable devices within segmented network zones with restricted inbound access. Device manufacturers should review and harden TLS handshake processing code to enforce strict length checks and bounds validation. Additionally, organizations should monitor threat intelligence feeds for any emerging exploit attempts targeting this vulnerability. Conducting security assessments and penetration tests focusing on TLS implementations in embedded systems can help identify and remediate potential attack vectors. Finally, maintain an inventory of all devices using NetX Duo to ensure comprehensive coverage during patch deployment.