CVE-2026-33592
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk31th percentile — higher than 31% of all known CVEs
Summary
An unauthenticated remote attacker can exhaust server memory via the FindServers Discovery Service in open62541. The serverUris field of FindServersRequest is not validated for length or array size, allowing an arbitrarily large string (up to ~3.9 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.
Risk Assessment
The attack can exhaust the OPC UA server's RAM, causing a denial of service (DoS) and disrupting critical industrial systems. The vulnerability is pre-session and bypasses all encryption configurations.
Recommendation
Immediately update open62541 to version 1.4.17, 1.5.5, or later, which includes validation of the serverUris field size. If an update is not possible, restrict OPC UA server access to trusted networks only.
Original NVD description (English source)
An unauthenticated remote attacker can exhaust server memory via the FindServers Discovery Service in open62541. The serverUris field of FindServersRequest is not validated for length or array size. An attacker can declare an arbitrarily large string (up to ~3.9 GB) delivered across intermediate chunks without ever sending the final chunk. The server buffers all chunks in RAM indefinitely until the SecureChannel times out. The attack is pre-session and bypasses all encryption configuration. The issue affects open62541: from 1.4.0 through 1.4.16, from 1.5.0 through 1.5.4, master.