CVE-2026-102718 in NetX Duo
Summary
by MITRE • 09/29/2026
hey,
`_nx_snmp_utility_object_id_get` in the NetX Duo SNMP addon does not validate the claimed OID data length against the actual buffer size when the OID uses BER multibyte length encoding, so a remote attacker can send a crafted SNMP packet with a multibyte OID length larger than the available buffer, causing the parser to read past the packet buffer boundary into adjacent heap memory. the OOB bytes are decoded as OID component values and written into the agents internal OID string buffer, corrupting agent state. on systems with memory protection the OOB read poses the risk of crashing the SNMP agent thread, causing denial of service. on bare metal embedded systems without memory protection the read silently succeeds and corrupts the agents internal state with heap data.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability identified in the NetX Duo SNMP addon centers on a critical input validation failure within the _nx_snmp_utility_object_id_get function, which is responsible for parsing Object Identifier (OID) components from incoming Simple Network Management Protocol packets. This specific flaw arises when the parser encounters BER Basic Encoding Rules multibyte length encoding for an OID value. In such scenarios, the software fails to verify that the claimed data length indicated by the encoded bytes does not exceed the actual remaining size of the packet buffer. Consequently, if a remote attacker crafts an SNMP request with a maliciously constructed OID containing a multibyte length field larger than the available buffer space, the parser proceeds without bounds checking, leading to an out-of-bounds read operation that accesses memory adjacent to the original packet buffer in the heap.
From a technical perspective, this issue represents a classic instance of improper input validation where the software trusts user-supplied data lengths without cross-referencing them against physical memory constraints. The BER encoding scheme allows for variable-length fields, and while standard implementations must carefully track byte offsets and remaining buffer sizes during parsing, this implementation neglects that safeguard specifically for multibyte length scenarios. As a result, the parser reads past the end of the allocated packet buffer into adjacent heap memory regions. These out-of-bounds bytes are then interpreted as valid OID component values and written into the agent's internal OID string buffer. This process corrupts the internal state of the SNMP agent by introducing arbitrary data derived from unrelated parts of the system's memory, potentially overwriting critical structures or pointers that govern subsequent protocol operations.
The operational impact of this vulnerability varies significantly depending on the underlying operating environment and its memory protection mechanisms. On systems equipped with hardware-enforced memory protection, such as those utilizing Memory Protection Units or similar features common in modern embedded processors, the out-of-bounds read triggers a fault exception when the CPU attempts to access unauthorized memory pages. This results in an immediate crash of the SNMP agent thread, leading to a denial of service condition where network management capabilities are temporarily unavailable until the system is restarted or the process is recovered. In contrast, on bare-metal embedded systems lacking such memory protection features, the out-of-bounds read may silently succeed without triggering any exceptions. However, this silent success leads to severe state corruption as heap data is misinterpreted and integrated into the agent's logic, potentially causing unpredictable behavior, incorrect management responses, or further exploitation vectors if the corrupted state influences subsequent control flow decisions.
This vulnerability aligns with CWE-125, Out-of-bounds Read, which describes situations where software reads memory beyond the intended boundary of a buffer due to insufficient validation of input data lengths. Furthermore, from an offensive security perspective, this flaw facilitates reconnaissance and potential denial of service attacks as described in MITRE ATT&CK technique T1498, Network Denial of Service, by allowing attackers to disrupt critical network management infrastructure remotely without authentication if the SNMP community strings are weak or default. To mitigate this risk, developers must implement rigorous bounds checking within the SNMP parser logic specifically for BER multibyte length fields. This involves calculating the total expected size of the OID component based on the encoded length and ensuring that this value does not exceed the remaining bytes in the current packet buffer before initiating any read operations. Additionally, integrating fuzzing tests targeting SNMP message structures into the continuous integration pipeline can help detect similar parsing flaws early in the development lifecycle, while deploying network segmentation policies to restrict access to SNMP services from untrusted networks provides a necessary defense-in-depth layer against remote exploitation attempts.