CVE-2019-19135: Insufficient Nonce Validation in Eclipse Milo Client
Summary
CVE-2019-19135: Insufficient Nonce Validation in Eclipse Milo Client. Affects org.eclipse.milo:sdk-client versions < 0.3.6. Fixed in 0.3.6. How to fix ↓
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Background
The Eclipse Milo Client is a software development kit (SDK) that provides a Java implementation of the OPC Unified Architecture (UA) protocol. It allows developers to create OPC UA clients to interact with OPC UA servers. OPC UA is a machine-to-machine communication protocol for industrial automation. The Milo Client supports various security features, including authentication and encryption.
The vulnerability identified as CVE-2019-19135 affects the Milo Client when certain conditions are met. Specifically, when the SecurityPolicy is set to None and the server has a defect causing it to send null, empty, or zeroed nonces, a credential replay attack can occur. This vulnerability can lead to unauthorized access and compromise of sensitive information.
Vulnerability Detail
The vulnerability arises due to insufficient nonce validation in the Eclipse Milo Client. Nonces are random numbers used to prevent replay attacks. In this case, when the SecurityPolicy is set to None, and the server sends null, empty, or zeroed nonces, the client fails to properly validate them. This allows an attacker to replay credentials and gain unauthorized access to the server.
To exploit this vulnerability, the following conditions must be met:
SecurityPolicyis set toNone- Username/password or X509-based authentication is used
- The server has a defect causing it to send null, empty, or zeroed nonces.
The impact of this vulnerability is credential replay, which can lead to unauthorized access and compromise of sensitive information.
How To Fix
Latest published version: 0.6.16 as of 22 Oct 2026
Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.3.6
This is the first release that contains the fix.
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Workaround
If updating the Eclipse Milo Client is not immediately feasible, a workaround is to avoid using username/password or X509-based authentication with a SecurityPolicy of None. Instead, consider using a different security policy or upgrading to a more recent version of the Milo Client that implements the relaxed treatment of validation.
Conclusion
The vulnerability identified as CVE-2019-19135 in the Eclipse Milo Client can lead to credential replay attacks, potentially resulting in unauthorized access and compromise of sensitive information. It is crucial to update the Milo Client to version 0.3.6 or later to mitigate this vulnerability. If immediate updating is not possible, consider using alternative authentication methods or upgrading to a version that implements the relaxed treatment of validation. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
The Eclipse Milo Client is a Java SDK that allows developers to create OPC UA clients for interacting with OPC UA servers in industrial automation.
OPC UA (Unified Architecture) is a machine-to-machine communication protocol for industrial automation. It provides a standardized way for different systems to exchange data and information.
A nonce is a random number used to prevent replay attacks. It is included in the communication between a client and a server to ensure the freshness and integrity of the data.
A credential replay attack is a type of attack where an attacker intercepts and replays previously captured credentials to gain unauthorized access to a system or service.
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