CVE-2026-11946
Description
A flaw was found in open62541. An unauthenticated remote attacker can exploit a vulnerability in the GetEndpoints Discovery Service by sending a malformed request with an excessively long, unvalidated endpointUrl field. This can lead to the server buffering large amounts of data indefinitely, causing server memory exhaustion and a Denial of Service (DoS) condition. This attack can occur before a secure session is established and bypasses encryption configurations.
Statement
A flaw was found in open62541, an open-source OPC UA implementation. The GetEndpoints Discovery Service does not validate the length of the endpointUrl field in GetEndpointsRequest. An unauthenticated remote attacker can declare an arbitrarily large string (up to ~4 GB) delivered via intermediate chunks without sending the final chunk. The server buffers all chunks in RAM indefinitely until the SecureChannel times out, causing memory exhaustion and denial of service. The attack is pre-session and bypasses all encryption configurations. Affected versions: 1.4.0 through 1.4.16, 1.5.0 through 1.5.4.
Mitigation
The issue has been fixed in v1.5.5.
Understanding the Weakness (CWE)
Other,Integrity,Availability
Technical Impact: Varies by Context; DoS: Resource Consumption (CPU); Modify Memory; Read Memory
When the quantity is not properly validated, then attackers can specify malicious quantities to cause excessive resource allocation, trigger unexpected failures, enable buffer overflows, etc.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
