High · published July 2, 2026
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.