The open62541 library versions 1.5.5 and earlier contain a vulnerability that can be triggered remotely by an attacker through crafted OPC UA service requests including CreateSubscription, CreateMonitoredItems (Sampling), Publish, TransferSubscriptions, and DeleteSubscriptions. Exploiting this flaw results in a denial of service condition, impacting the availability of the affected system. The vulnerability does not affect confidentiality or integrity. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, confirming network attack vector, low attack complexity, no privileges or user interaction required, and high impact on availability. The affected versions explicitly include =1.4.11.1-1 and =1.4.11.1-1build1. There is no information provided about patches or vendor advisories, and no known exploits in the wild have been reported.

Successful exploitation results in denial of service, causing unavailability of the affected open62541 service. There is no impact on confidentiality or integrity. The medium severity rating reflects the significant availability disruption possible without requiring authentication or user interaction.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Until a patch is available, consider limiting network exposure of the affected service and monitoring for unusual OPC UA request patterns targeting subscription management functions.