CVE-2026-11946: OPEN62541 Project / o6 Automation GmbH OPEN62541

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

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. An attacker can declare an arbitrarily large string (up to ~4.09 GB via the UInt32 length field) 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 configurations. The issue affects open62541: from 1.4.0 through 1.4.16, from 1.5.0 through 1.5.4, master.

Affected products

• OPEN62541 Project / o6 Automation GmbH OPEN62541: from 1.4.0, up to and including 1.4.16; from 1.5.0, up to and including 1.5.4

Published 2026-07-02. Last modified 2026-07-02.