CVE-2026-63559 in open62541
Summary
by MITRE • 07/31/2026
An integer overflow in the UA_Variant arrayDimensions product computation in open62541 may allow a remote attacker to read out-of-bounds heap memory, potentially disclosing sensitive information.
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Analysis
by VulDB Data Team • 07/31/2026
The vulnerability under discussion involves an integer overflow within the UA_Variant arrayDimensions product computation component of the open62541 library, which represents a widely used open-source implementation of the OPC UA (Open Platform Communications Unified Architecture) protocol. This flaw exists in the memory management and data handling mechanisms of the library, specifically affecting how array dimensions are processed during variant data type operations. The integer overflow occurs when computing the product of array dimensions, where the calculation fails to properly validate or handle cases where dimension values exceed the maximum representable integer value for the underlying data type.
The technical nature of this vulnerability stems from improper input validation and arithmetic overflow handling within the library's core processing functions. When an attacker provides maliciously crafted array dimension values that cause integer overflow during the product computation, the resulting incorrect calculation can lead to memory allocation issues. The overflow condition allows the system to compute a smaller value than intended, which when used as a size parameter for heap memory allocation or indexing operations can result in accessing memory locations beyond the allocated buffer boundaries. This out-of-bounds memory access enables potential information disclosure through read operations that may retrieve data from adjacent memory segments containing sensitive information such as stack contents, heap metadata, or other application data.
From an operational perspective, this vulnerability presents a significant security risk for systems relying on open62541 for OPC UA communications, particularly in industrial control systems, SCADA networks, and IoT deployments where such libraries are commonly integrated. Remote attackers can exploit this vulnerability without requiring authentication, making it particularly dangerous in networked environments where OPC UA servers may be exposed to untrusted clients. The impact extends beyond simple information disclosure to potentially enable more sophisticated attacks, as the leaked memory contents could contain cryptographic keys, session tokens, or other sensitive data that could facilitate further exploitation. This vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions, and represents a classic example of how improper arithmetic handling can lead to memory safety issues.
The attack surface for this vulnerability is broad given the widespread adoption of open62541 across various industrial and commercial applications. Systems utilizing OPC UA protocols for data exchange, particularly those implementing variant data types with dynamic array dimensions, are at risk. The exploitability factor is high since the vulnerability can be triggered through normal protocol operations without requiring special privileges or complex attack chains. Organizations should consider this vulnerability in the context of ATT&CK framework tactic TA0001 (Initial Access) and technique T1071.004 (Application Layer Protocol: SSH), as it represents a potential entry point for attackers seeking to gather intelligence about system configurations and sensitive data through memory disclosure attacks.
Mitigation strategies should include immediate patching of affected open62541 versions, implementation of input validation controls on array dimension parameters, and deployment of network segmentation to limit exposure. Additionally, organizations should consider implementing runtime protections such as address space layout randomization, stack canaries, and heap-based memory protection mechanisms. Regular security assessments of OPC UA implementations, including code reviews focused on integer arithmetic operations and memory handling patterns, are essential for identifying similar vulnerabilities in custom applications built on top of the open62541 library. The vulnerability demonstrates the critical importance of robust input validation and proper integer overflow protection in security-critical software components that handle user-provided data.