CVE-2026-50032 in libIEC61850
Summary
by MITRE • 07/24/2026
A NULL pointer dereference in the MMS Write Named Variable List handler, which may allow a network adjacent attacker to crash the server by sending a WriteRequest with an empty listOfData field.
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Analysis
by VulDB Data Team • 07/24/2026
This vulnerability represents a critical null pointer dereference flaw within the MMS (Manufacturing Message Specification) protocol implementation, specifically affecting the Write Named Variable List handler component. The issue occurs when processing WriteRequest messages containing an empty listOfData field, creating a scenario where the application attempts to access memory at a NULL address during normal operation. This type of vulnerability falls under CWE-476 which categorizes null pointer dereference conditions as serious weaknesses that can lead to application crashes or system instability. The attack vector requires network adjacency, meaning an attacker must be able to communicate directly with the vulnerable server over the network without requiring authentication or complex exploitation techniques.
The technical execution of this vulnerability involves the MMS protocol's named variable list handler failing to properly validate input data before attempting to process it. When a WriteRequest message is received with an empty listOfData field, the system does not perform adequate null checks or validation routines that would normally precede memory access operations. This failure allows the server application to proceed with processing logic that assumes the presence of valid data structures, ultimately resulting in a segmentation fault or access violation when attempting to dereference a NULL pointer during the variable list writing operation.
From an operational impact perspective, this vulnerability creates significant risk for industrial control systems and manufacturing environments that rely on MMS protocol implementations for device communication and data management. The ability to remotely crash a server through a simple malformed request represents a denial of service attack vector that could disrupt critical manufacturing processes or monitoring systems. The vulnerability affects the availability aspect of the CIA triad, potentially causing production downtime, data loss, or system unavailability when attackers target servers running affected MMS implementations. This type of attack aligns with ATT&CK technique T1499.004 which covers network denial of service attacks targeting services and infrastructure.
The mitigation strategies for this vulnerability should include immediate input validation and null pointer checking within the MMS protocol handler implementation. Developers must implement proper defensive programming practices that validate all incoming data structures before processing, particularly ensuring that listOfData fields are not only present but also contain valid references before any memory access operations occur. Additionally, implementing robust error handling and graceful degradation mechanisms would prevent the application from crashing when encountering malformed input. System administrators should consider network segmentation and access controls to limit exposure of MMS services to trusted networks only, while also monitoring for unusual traffic patterns that might indicate exploitation attempts. The fix requires modifications to the protocol handler code to include comprehensive validation routines that check for NULL values and empty data structures before proceeding with any processing logic that might lead to memory access violations.