CVE-2026-18784

A vulnerability was found in open62541 up to version 1.5.5, affecting the function responseReadNamespacesArray in src/client/ua_client_connect.c. Manipulation of the Server_NamespaceArray argument causes a null pointer dereference, potentially leading to application crashes. The attack can be executed remotely but requires high complexity and is difficult to exploit.

In open62541 v1.5.5, the server-side AddReferences implementation contains an incomplete validation flaw for non-local ExpandedNodeId targets. A remote attacker can send a crafted AddReferencesRequest with an empty targetServerUri and a non-zero targetNodeId.serverIndex, causing the target node pointer to remain NULL while execution continues.

open62541 1.5.0 before 1.5.7 contains an integer overflow in UA_DataType_fromStructureDescription() that wraps the 16-bit memSize field for large custom structure definitions. A malicious OPC UA server can supply DataType definitions via UA_Client_getRemoteDataTypes(), causing decodeBinaryStructure() to overflow the heap, crashing clients or enabling code execution.

A vulnerability was detected in open62541 up to 1.5.5 in the function UA_DataValue_backend_copyRange of the History Backend component. Manipulation leads to use after free. The attack can be launched remotely, and the exploit is publicly available.

Buffer Overflow vulnerability in open62541 v1.5.5 allows a remote attacker to cause a denial of service via the Service_Call, which validates input arguments against runtime-resolved InputArguments metadata.

In open62541 1.5.5, a server-side use-after-free exists in the local MonitoredItem callback path. The issue occurs when UA_Subscription_localPublish continues to use the current UA_Notification after a callback invokes UA_Server_deleteMonitoredItem for the current local MonitoredItem. This allows a remote attacker to cause a denial of service.

An issue in open62541 v.1.5.5 and before allows a remote attacker to cause a denial of service via the NodeManagement type-instantiation logic component.

open62541 1.5.5 contains a buffer-overflow in the high-level attribute reading logic in src/client/ua_client_highlevel.c. This allows a remote attacker to cause a denial of service.

An issue in open62541 v.1.5.5 and before allows a remote attacker to cause a denial of service via the UA_Client_getRemoteDataTypes component.

open62541 version 1.5.5 contains a heap-based buffer overflow in the default HistoryRead path when the default history database is used with the memory backend.