CVE-2026-66364 in libiec61850
Summary
by MITRE • 07/31/2026
The GOOSE payload parser contains a boundary handling flaw that can be triggered by a single unauthenticated Layer 2 multicast frame on the process bus. When processing specific payload fields, an attacker controlled inner element length may exceed its enclosing length, causing the parser to over read by one byte. This out-of-bounds read reliably terminates the subscriber process, resulting in a denial-of-service condition.
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Analysis
by VulDB Data Team • 07/31/2026
The vulnerability under examination represents a critical boundary handling flaw within GOOSE payload parsers that operates at the Layer 2 network level within industrial control systems. This issue stems from improper validation of payload field lengths during the parsing process, specifically affecting the communication protocols used in power systems and other industrial environments where GOOSE (Generic Object Oriented Substation Event) messages facilitate rapid transmission of critical control information between networked devices.
The technical implementation flaw occurs when an attacker crafts a malicious Layer 2 multicast frame containing specially constructed payload data that manipulates length fields within the GOOSE message structure. The vulnerability manifests when processing specific payload elements where an attacker-controlled inner element length parameter exceeds the bounds of its enclosing container, creating a condition where the parser attempts to read beyond allocated memory boundaries. This particular out-of-bounds read operation occurs due to insufficient validation of nested field lengths and improper boundary checking mechanisms within the parsing routine.
The operational impact of this vulnerability extends beyond simple service disruption as it creates a reliable denial-of-service condition that terminates subscriber processes executing the affected GOOSE parser implementations. When the parser encounters the malformed payload structure, the out-of-bounds memory access causes the target process to crash or terminate unexpectedly, effectively removing the system from operational capability within the industrial network infrastructure. This termination affects not only the immediate parsing functionality but can cascade through connected systems that depend on the continuous operation of these subscriber processes for maintaining control loop stability.
The vulnerability aligns with CWE-129: Improper Validation of Array Index and CWE-787: Out-of-bounds Write conditions commonly found in industrial protocol implementations where memory safety checks are insufficient. From an ATT&CK framework perspective, this represents a privilege escalation vector through denial-of-service attacks that can disrupt operational technology systems, potentially affecting the CIA triad of security by compromising availability and integrity of critical control information flows. The attack surface is particularly concerning given that the exploit requires only a single unauthenticated multicast frame, making it easily executable from any position within the Layer 2 network segment without requiring prior access credentials or elevated privileges.
Mitigation strategies should focus on implementing robust boundary validation mechanisms within the parser implementations to ensure proper field length checking before memory access operations occur. Network segmentation and monitoring solutions should be deployed to detect anomalous GOOSE traffic patterns, while implementing ingress filtering to prevent unauthorized multicast frames from entering critical network segments. Additional defensive measures include deploying intrusion detection systems specifically configured to identify malformed GOOSE payload structures and establishing process monitoring for rapid detection of subscriber process termination events. Organizations should also consider implementing redundant communication paths and fail-safe mechanisms to maintain system functionality during potential exploitation attempts, ensuring operational continuity in mission-critical industrial environments where availability is paramount for safety and reliability.