CVE-2026-102760 in NetX Duo
Summary
by MITRE • 09/29/2026
When NetX Secure is built with `NX_SECURE_KEY_CLEAR`, every TLS record sent on an active session is wiped after it has been handed to TCP. By then the TCP layer owns the packet chain and may already have released it to the packet pool. The wipe therefore writes zeros into packets that are free or in use by another thread, and when a reused packet's pointers no longer describe the old data, the length of the wipe underflows and it runs past the end of the packet pool.
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Analysis
by VulDB Data Team • 09/29/2026
The vulnerability described involves a critical memory safety flaw within the NetX Secure networking stack, specifically triggered during TLS record transmission when the NX_SECURE_KEY_CLEAR configuration option is enabled. This feature is designed to enhance security by wiping sensitive cryptographic keys and data from memory after they are no longer needed, thereby preventing potential key leakage through memory dumps or other side-channel attacks. However, the implementation of this wipe operation contains a fundamental race condition and logic error regarding packet ownership and lifecycle management within the TCP/IP stack architecture.
The core technical flaw arises from an incorrect assumption about when data is safely isolated from system-wide access. The vulnerability occurs because the wiping process initiates after the TLS record has been handed over to the Transmission Control Protocol layer for transmission. At this specific point in the network stack, ownership of the packet chain transfers from the application or security module to the TCP implementation. Once transferred, the TCP layer may immediately release these packets back into a shared memory pool for reuse by other threads or subsequent connections without ensuring that all hardware and software references have been fully flushed or completed. Consequently, when NetX Secure attempts to zero out the memory associated with the TLS record, it is writing zeros into memory regions that are either already freed or actively being used by concurrent processes.
This misalignment of ownership leads directly to a severe buffer underflow condition. The wipe operation relies on length fields contained within the packet descriptors to determine how much data needs to be cleared. However, because the packets have been released back to the pool, their internal pointers and metadata may no longer accurately reflect the original extent of the TLS record data. Specifically, if the pointer arithmetic or length calculation fails due to the altered state of the freed memory structure, the calculated wipe size can become negative or erroneously large in a way that causes an underflow when treated as an unsigned integer. This results in the write operation running past the boundaries of the intended packet buffer and into adjacent memory regions within the pool.
The operational impact of this vulnerability is severe and multifaceted. First, it constitutes a classic out-of-bounds write, which can corrupt neighboring data structures, overwrite critical control information such as heap metadata or other thread-local variables, and potentially lead to application crashes or denial of service conditions due to memory corruption. Second, because the wipe targets packets that are in active use by other threads, it effectively destroys valid network traffic being processed concurrently. This results in silent packet loss, connection resets, and significant degradation of network reliability for all users sharing the same system resources. In worst-case scenarios, an attacker who can influence or observe network traffic patterns might exploit this memory corruption to achieve arbitrary code execution if they can control the data written into adjacent structures, although the primary immediate effect is stability and integrity compromise rather than direct privilege escalation.
From a standards perspective, this vulnerability maps directly to CWE-787: Out-of-bounds Write, as it involves writing data beyond the allocated buffer boundaries due to incorrect length calculations. It also relates to CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization, highlighting the race condition between packet handoff and memory wiping. In terms of attack vectors, this aligns with ATT&CK technique T1499: Endpoint Denial of Service, as the corruption can destabilize the host system, and potentially T1053: Scheduled Task/Job if the resulting instability triggers automated recovery mechanisms that could be manipulated.
Mitigation strategies must address both the architectural design flaw and the specific implementation error. The most effective solution is to ensure that memory wiping occurs only after all references to the data have been definitively relinquished by the system, which may require implementing a synchronous flush or refcounting mechanism before initiating the secure wipe. Alternatively, developers should allocate dedicated buffers for TLS records that are not returned to the general packet pool until they are completely processed and acknowledged at lower layers of the stack. If immediate wiping is required for compliance reasons, it must be performed on copies of the data rather than the original packets owned by TCP/IP, or a memory barrier must be enforced to guarantee that no other thread accesses the buffer during the wipe operation. Additionally, adding bounds checking before any memory zeroization routine can prevent underflow conditions from causing out-of-bounds writes, serving as a defensive coding practice even if the root cause is architectural.