CVE-2026-56758 in libiec61850
Summary
by MITRE • 07/31/2026
The ACSE layer contains a flaw in the processing of AARQ PDUs during MMS connection establishment. When parsing certain fields within the calling AP title, an attacker controlled length value of zero or one may cause the parser to read past the end of a heap buffer.
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Analysis
by VulDB Data Team • 07/31/2026
This vulnerability resides within the ACSE layer of MMS protocol implementations, specifically during the connection establishment phase when processing AARQ PDUs. The flaw manifests as a classic buffer overflow condition that occurs when parsing the calling AP title field, where an attacker can manipulate the length parameter to values of zero or one. This manipulation causes the parser to traverse beyond the allocated heap buffer boundaries, potentially leading to memory corruption and arbitrary code execution.
The technical implementation involves improper bounds checking within the AARQ PDU processing logic, creating a condition where the parser assumes valid input lengths while actually encountering attacker-controlled data that can cause memory access violations. This vulnerability falls under CWE-129 Input Validation and CWE-787 Out-of-bounds Write categories, representing a critical security weakness in protocol implementation that allows for remote code execution through malformed packet processing. The attack surface is particularly concerning as it occurs during the initial connection establishment phase, meaning an attacker can exploit this vulnerability before legitimate authentication or authorization mechanisms are engaged.
From an operational impact perspective, this vulnerability presents significant risk to industrial control systems and manufacturing environments that rely on MMS protocols for communication between devices and controllers. The ability to cause heap buffer overflows during connection establishment allows attackers to potentially execute arbitrary code on affected systems, leading to complete system compromise. This vulnerability aligns with ATT&CK technique T1203 Exploitation for Client Execution, where attackers leverage protocol parsing flaws to gain remote access to target systems.
Mitigation strategies should include implementing strict bounds checking for all parsed fields within the AARQ PDU processing, particularly focusing on length validation for the calling AP title field. Network segmentation and access controls should be implemented to limit exposure of affected systems to untrusted networks or users. Regular protocol implementation reviews should be conducted to identify similar buffer overflow vulnerabilities in other protocol layers. Additionally, implementing intrusion detection systems that can monitor for anomalous AARQ PDU patterns may help detect exploitation attempts before successful compromise occurs. The vulnerability demonstrates the critical importance of proper memory management and input validation in protocol implementations, particularly in industrial environments where system integrity is paramount.