CVE-2026-66360 in libiec61850
Summary
by MITRE • 07/31/2026
The ISO Presentation layer contains a flaw in the handling of specific parameters during normal mode negotiation. A missing length check in the processing of the encoded presentation data allows an attacker controlled field with a zero length value to trigger a bounded heap over read. This condition occurs before MMS session establishment, a crafted TCP/102 connection attempt can trigger the issue. The resulting over read causes the process to terminate, leading to a denial of service condition.
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Analysis
by VulDB Data Team • 07/31/2026
The vulnerability under examination resides within the ISO Presentation layer implementation, specifically manifesting during normal mode negotiation processes where presentation data is being encoded and processed. This flaw represents a critical security weakness that enables remote attackers to induce denial of service conditions through carefully crafted network communications. The issue stems from inadequate input validation mechanisms that fail to properly verify the length parameters associated with presentation data elements, creating an exploitable condition that can be triggered prior to session establishment.
The technical root cause involves a missing length check during the processing of encoded presentation data within the ISO Presentation layer. When an attacker-controlled field containing a zero length value is processed, the system fails to validate this parameter before proceeding with memory operations. This absence of proper boundary checking creates a heap over read condition where the application attempts to access memory locations beyond the allocated buffer boundaries. The vulnerability specifically occurs in the context of TCP port 102 connections which are commonly used for MMS (Manufacturing Message Specification) communications in industrial control systems and SCADA environments.
The operational impact of this vulnerability extends beyond simple service disruption as it represents a pre-authentication denial of service condition that can be exploited by remote attackers without requiring any prior authentication credentials. The heap over read results in process termination, effectively disabling the targeted system's ability to handle presentation layer communications until manual intervention occurs. This type of vulnerability particularly affects industrial control systems where continuous operation is critical, as the denial of service can disrupt production processes and create significant operational downtime.
This vulnerability aligns with CWE-129 which addresses insufficient validation of length of input buffers, representing a fundamental weakness in input validation mechanisms that allows attackers to manipulate buffer boundaries through crafted inputs. The attack vector follows patterns consistent with ATT&CK technique T1499.004 for network denial of service attacks, where adversaries target specific protocols or services to disrupt availability. The fact that this occurs before MMS session establishment indicates the vulnerability exists in the initial connection handling phase, making it particularly dangerous as it can prevent legitimate users from establishing communication with the system.
Mitigation strategies should focus on implementing proper input validation mechanisms that enforce length checks on all presentation data parameters before processing begins. System administrators should consider implementing network segmentation and access controls to limit exposure of affected systems to untrusted networks. Additionally, applying vendor-specific patches or updates that address the missing length validation in the ISO Presentation layer implementation represents the most effective long-term solution. Organizations should also implement monitoring solutions capable of detecting anomalous TCP/102 connection attempts that may indicate exploitation attempts, particularly those involving zero-length parameter values in presentation data structures.
The vulnerability demonstrates the importance of robust input validation in protocol implementations and highlights the potential for seemingly minor oversights in boundary checking to result in significant availability impacts. Given that this affects industrial control systems and manufacturing communication protocols, the risk assessment should consider both operational technology security requirements and the potential for cascading failures in connected systems that rely on these communication channels for proper operation and coordination.