CVE-2026-66720 in libiec61850
Summary
by MITRE • 07/31/2026
The GOOSE subscriber component improperly validates the UTC timestamp field in unauthenticated IEC 61850 GOOSE (EtherType 0x88B8) Layer-2 multicast messages. A specially crafted GOOSE frame containing an undersized timestamp field can trigger a heap out-of-bounds read during message processing, causing the process to crash and resulting in a denial-of-service condition.
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Analysis
by VulDB Data Team • 07/31/2026
The vulnerability described represents a critical heap-based out-of-bounds read condition within the GOOSE subscriber component of IEC 61850 communication systems, which operates at Layer-2 using EtherType 0x88B8 multicast messages. This flaw specifically targets the validation mechanism for UTC timestamp fields in GOOSE frames, where the system fails to properly verify the size and structure of incoming timestamp data. The issue arises from insufficient input validation routines that do not adequately check the boundaries of timestamp fields, allowing malformed data to bypass normal processing safeguards and potentially execute malicious code patterns.
The technical exploitation of this vulnerability occurs when an attacker crafts a specially formatted GOOSE frame containing an undersized timestamp field that falls below the expected minimum size requirements defined by the IEC 61850 standard. During normal message processing, the subscriber component attempts to read from heap memory locations beyond the allocated buffer boundaries when parsing this malformed timestamp data. This improper validation creates a condition where the system's memory access patterns exceed allocated memory limits, leading to unpredictable behavior including segmentation faults and process termination.
This vulnerability directly impacts the operational integrity of IEC 61850-based protection and control systems that rely on GOOSE messaging for real-time communication between intelligent electronic devices. The denial-of-service condition resulting from process crashes can severely disrupt critical infrastructure operations, particularly in power grid automation where timely GOOSE message delivery is essential for protective relaying functions. The cascading effect of multiple process failures across interconnected devices could lead to widespread system instability and potential safety hazards in industrial control environments.
The vulnerability aligns with CWE-129 and CWE-787 categories from the Common Weakness Enumeration catalog, specifically addressing improper input validation and out-of-bounds read conditions in memory management. From the MITRE ATT&CK framework perspective, this weakness maps to techniques involving privilege escalation and denial-of-service attacks through application-level vulnerabilities. The attack surface is particularly concerning in industrial environments where network monitoring tools may not detect such Layer-2 attacks, and where security controls are often focused on higher protocol layers.
Mitigation strategies should include implementing robust input validation routines that enforce minimum timestamp field sizes and proper boundary checking before memory access operations occur. System administrators should deploy network segmentation measures to limit unauthorized access to GOOSE message streams and implement monitoring solutions capable of detecting malformed GOOSE frames. Additionally, regular firmware updates from vendors addressing this specific heap management issue are crucial for maintaining system integrity, while network intrusion detection systems should be configured to alert on unusual GOOSE message patterns that may indicate exploitation attempts.