CVE-2026-67856

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.

An unauthenticated remote attacker can exhaust server memory via the GetEndpoints Discovery Service in open62541. The endpointUrl field of GetEndpointsRequest is not validated for length, allowing an arbitrarily large string (up to ~4.09 GB) to be declared and delivered across intermediate chunks without ever sending the final chunk. The server buffers all chunks in RAM indefinitely until the SecureChannel times out.

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.

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.

Buffer overflow vulnerability in open62541 v1.5.5 allows a remote attacker to cause a denial of service via Discovery/LDS handling.