CVE-2026-102728 in NetX Duo
Summary
by MITRE • 09/29/2026
Two client-side TLS/DTLS handshake parsers in NetX Secure read fields from a server-supplied message before validating that the message is long enough to contain them. Both are bounded out-of-bounds reads on a remotely reachable path, both are reached from a TLS or DTLS client connecting to a malicious or malformed server, and both have the same shape: the bounds check exists and returns the correct status, but it runs after the read it is meant to guard.
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Analysis
by VulDB Data Team • 09/29/2026
The vulnerability described involves two distinct flaws within the NetX Secure library's implementation of TLS and DTLS client-side handshake parsers. These vulnerabilities are classified as out-of-bounds reads, specifically bounded off-by-one or similar boundary violations where memory access occurs before length validation. In a typical secure software architecture, input data received from an external source must be validated for size and structure prior to any parsing operations that interpret the content of that buffer. However, in this specific instance, the code logic is inverted; the parser attempts to extract fields from the server-supplied message immediately upon receipt, without first confirming that the incoming packet contains sufficient bytes to support those extraction operations. This architectural flaw creates a scenario where an attacker can trigger memory disclosure by sending specially crafted handshake messages that are shorter than expected but still valid enough to reach the parsing logic before the length check fails or returns control.
From a technical perspective, these flaws represent classic pre-validation read errors. The TLS and DTLS protocols rely on structured binary data for handshakes, where specific fields have fixed sizes such as certificate lengths, cipher suite identifiers, or extension headers. When the parser reads these fields before verifying that the total message length is adequate, it may access memory locations beyond the allocated buffer boundary. Although the subsequent bounds check correctly identifies the error and returns a status indicating an invalid message, the damage has already been done at the moment of the read operation. In many programming environments, particularly those using C or similar low-level languages common in embedded systems like NetX Secure, reading out-of-bounds memory can lead to information disclosure, where sensitive data residing adjacent to the buffer is leaked into application variables or logs. It may also cause undefined behavior depending on how the operating system handles such access, potentially leading to crashes that facilitate denial of service attacks if exception handling mechanisms are not robustly implemented around these parsing routines.
The operational impact of this vulnerability is significant due to its remote reachability and client-side nature. Since it affects the TLS or DTLS client connecting to a server, an attacker positioned as a malicious man-in-the-middle or controlling a rogue access point can exploit this by presenting a malformed handshake message during the initial connection phase. For DTLS, which is often used in constrained environments like IoT devices, network-based attacks are particularly feasible because UDP lacks the stateful protections of TCP. The exploitation does not require authentication, allowing any remote actor to attempt the attack. While the primary impact appears to be information disclosure through memory leaks, such vulnerabilities can sometimes be chained with other flaws or leveraged to destabilize the application stack, leading to service disruption for devices relying on secure communications in critical infrastructure or industrial control systems.
Mitigation strategies must focus on correcting the order of operations within the parsing logic. The immediate fix involves moving the length validation checks to precede any field extraction from the server-supplied buffer. Developers should ensure that every read operation is guarded by a prior assertion that the remaining data size exceeds the required field width. Additionally, implementing strict input sanitization and employing static analysis tools configured to detect pre-validation reads can help identify similar patterns in other parts of the codebase. For organizations using NetX Secure, applying vendor-provided patches or updates that address these specific CVEs is essential. In the interim, network-level controls such as deep packet inspection firewalls may offer some protection by detecting and blocking malformed TLS/DTLS handshakes before they reach vulnerable endpoints, although this is not a substitute for fixing the underlying code defect.
This vulnerability aligns with CWE-125 Out-of-bounds Read in the Common Weakness Enumeration taxonomy, which describes accessing memory beyond the intended boundary of an object. Furthermore, from the perspective of the MITRE ATT&CK framework, this flaw facilitates reconnaissance and potentially privilege escalation if combined with other vulnerabilities, falling under techniques related to collection or discovery via network sniffing or protocol manipulation. The lack of proper input validation before processing is a fundamental security design error that undermines the integrity of secure communication channels. Addressing these issues requires not only patching the specific instances but also reinforcing development practices to enforce pre-condition checks for all external inputs, ensuring that data validity is established before any interpretation occurs.