CVE-2026-102712 in NetX Duo
Summary
by MITRE • 09/29/2026
On the first DTLS ClientHello, the parser copies a device-claimed session_id length and validates the
ciphersuite-list length against the total record length instead of the remaining bytes. An unauthenticated
peer drives an OOB source read of up to 255 bytes, and those bytes are echoed verbatim into the outgoing
ServerHello, disclosing adjacent process memory over the network. The crash variant fires on the first
packet.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/29/2026
The vulnerability described constitutes a critical out-of-bounds (OOB) read flaw within the DTLS protocol implementation, specifically triggered during the initial ClientHello message processing phase. This issue arises from an incorrect validation logic in the parser responsible for handling session identifiers and cipher suite lists. Instead of validating the length fields against the remaining bytes available in the current record buffer, the software erroneously compares them against the total record length. This fundamental miscalculation allows a malicious, unauthenticated peer to craft a specially constructed DTLS ClientHello packet that exploits this boundary check failure. By manipulating the session_id length field and potentially other related fields, an attacker can cause the parser to read memory locations beyond the intended buffer boundaries.
The operational impact of this flaw is severe, as it leads directly to information disclosure through side-channel leakage or direct memory dumping. When the out-of-bounds source read occurs, up to 255 bytes of adjacent process memory are accessed and subsequently echoed verbatim into the outgoing ServerHello response message sent back to the attacker. This mechanism effectively transforms a standard handshake failure or error condition into a powerful remote information leak vector. The disclosed data may contain sensitive cryptographic keys, internal application states, stack canaries, or other confidential information residing in the process memory space adjacent to the DTLS buffer. Because this behavior occurs on the very first packet of the connection attempt, it requires no prior authentication state and does not depend on complex multi-step handshake negotiations, making exploitation straightforward and highly reliable for an attacker with network access.
From a classification perspective, this vulnerability aligns closely with CWE-125: Out-of-bounds Read, as the application reads data beyond the allocated buffer limits. Furthermore, it maps to ATT&CK technique T1083: File and Directory Discovery if the leaked memory contains file system paths or configuration details, but more accurately fits within general Information Exfiltration over a Command and Control channel (T1048) when considering the network transmission of sensitive data. The specific context of TLS/DTLS handshake manipulation also relates to CWE-20: Improper Input Validation, as the root cause is the failure to correctly validate input lengths against the actual available buffer space rather than an incorrect total length metric.
Mitigation strategies must focus on correcting the validation logic within the DTLS parser implementation. Developers should ensure that all length fields extracted from network packets are validated against the remaining bytes in the current record or message buffer, not the total size of the underlying data structure. Implementing strict bounds checking before any memory copy operations is essential to prevent out-of-bounds reads. Additionally, deploying runtime protection mechanisms such as Address Sanitizers during testing phases can help identify similar logic errors earlier in the development lifecycle. For immediate defense-in-depth measures, network-level controls like intrusion detection systems should be configured to flag anomalous DTLS packet sizes or unusual patterns in handshake messages that deviate from standard protocol behavior. Updating to patched versions of the affected software is the primary remediation step for production environments exposed to this vulnerability.