CVE-2026-102723 in NetX Duo
Summary
by MITRE • 09/29/2026
NULL Pointer Dereference on MSRP Attribute Table Exhaustion
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Analysis
by VulDB Data Team • 09/29/2026
The vulnerability identified as NULL pointer dereference during Media Stream Relay Protocol attribute table exhaustion represents a critical reliability and availability risk within systems implementing the Session Initiation Protocol extensions for real-time media streams. This flaw specifically targets the memory management routines responsible for handling dynamic allocation of data structures associated with MSRP sessions. When an attacker or malicious actor initiates a high volume of connection requests or sends malformed messages that trigger repeated allocations without corresponding deallocations, the system's attribute table can become exhausted. In such scenarios, subsequent attempts to access entries in this depleted table result in functions returning null pointers instead of valid memory addresses. The software fails to implement adequate defensive programming practices by not checking for these null returns before dereferencing them, leading directly to a segmentation fault or application crash.
From a technical perspective, the root cause lies in insufficient input validation and error handling within the MSRP implementation's core logic. When resources are scarce due to table exhaustion, standard library functions often return NULL to indicate failure. However, legacy codebases or poorly maintained modules frequently assume successful allocation without verifying the pointer validity. This oversight allows a remote attacker to exploit the condition by flooding the service with requests that consume available slots in the attribute table. Once the limit is reached, any further processing of MSRP attributes will trigger the null dereference exception. This type of flaw is commonly categorized under CWE-476, which defines NULL Pointer Dereference as a design error where code assumes a non-null pointer value when it can be null. Such errors are particularly dangerous in network-facing services because they do not require complex exploitation techniques like buffer overflows or arbitrary code execution; instead, they rely on resource exhaustion to trigger the crash.
The operational impact of this vulnerability is primarily centered around denial of service conditions for both the affected server and potentially connected clients. Since MSRP is often used alongside SIP for establishing multimedia sessions in VoIP environments, a crash in the MSRP handler can disrupt ongoing voice or video calls. Furthermore, if the application does not have robust auto-restart mechanisms configured by system administrators, the entire signaling stack may become unresponsive until manual intervention occurs. This creates an opportunity for persistent availability attacks where adversaries can repeatedly trigger crashes to keep critical communication infrastructure offline. In enterprise environments relying on unified communications platforms, such instability can lead to significant productivity losses and service level agreement violations.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. Organizations should apply vendor-provided security updates that address the specific memory management logic in their MSRP implementations. These patches typically include checks for null pointers before dereferencing them, ensuring graceful error handling rather than catastrophic failure. Additionally, implementing rate limiting and connection throttling at the network perimeter can help mitigate resource exhaustion attacks by preventing a single source from monopolizing available slots in the attribute table. Security teams should also monitor logs for patterns indicative of MSRP flooding or unusual spikes in session establishment attempts. Adopting static analysis tools during development phases to detect potential null dereferences early in the software lifecycle is another recommended practice aligned with secure coding standards like OWASP MASVS and CWE guidelines.