CVE-2026-67858
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk39th percentile - higher than 39% of all known CVEs
Summary
Buffer overflow vulnerability in open62541 1.5.5 when the Local Discovery Server (LDS) is built with multicast discovery enabled through the MDNSD backend. An unauthenticated remote attacker can send a RegisterServer or RegisterServer2 request containing many unique discoveryUrls, causing a denial of service.
Risk Assessment
The attack can cause unavailability of the LDS server, disrupting OPC UA server discovery in the network.
Recommendation
Update open62541 to a patched version. If possible, disable multicast discovery or restrict access to LDS.
Other vulnerabilities in open62541
See all- CVE-2026-15690Low
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.
- CVE-2026-11946High
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.
- CVE-2026-67870Critical
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.
- CVE-2026-67869High
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.
- CVE-2026-67863High
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.
- CVE-2026-67864High
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.
- CVE-2026-67862High
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.
- CVE-2026-67861High
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.
- CVE-2026-67860High
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.
- CVE-2026-67859High
Buffer overflow vulnerability in open62541 v1.5.5 allows a remote attacker to cause a denial of service via Discovery/LDS handling.
Original NVD description (English source)
Buffer Overflow vulnerability exists in open62541 1.5.5 when the Local Discovery Server (LDS) is built with multicast discovery enabled through the MDNSD backend. An unauthenticated remote attacker can send a RegisterServer or RegisterServer2 request containing many unique discoveryUrls. This allows remote attackers to cause a denial of service.