CVE-2026-54155

node-opcua, a TypeScript/Node.js implementation of the OPC UA industrial communication protocol, fails to verify that the trailing bytes of a decrypted RSA-OAEP password blob match the current session's serverNonce in versions before 2.166.0. An unauthenticated remote attacker can fetch the server's public key via the GetEndpoints service, craft a malicious UserNameIdentityToken whose length field decodes to an empty password, and authenticate to any account whose isValidUser check accepts an empty password. The missing nonce binding also lets an attacker replay a captured UserNameIdentityToken ciphertext from one session in another, and when SecurityMode=None is permitted the separate client-signature safeguard is removed. Any deployment running node-opcua < 2.166.0 as an OPC UA server with username/password authentication is affected, especially those with permissive security policies or accounts that allow blank passwords. No public proof-of-concept exists and the flaw is not on the CISA KEV list, so exploitation in the wild is not known.

What to do: Upgrade node-opcua to version 2.166.0 or later, which adds serverNonce verification. Until patched, audit user accounts for any that accept an empty password and remove or harden them, disable SecurityMode=None and require signing/encryption security policies, and rotate credentials for accounts whose tokens may have been captured, since previously intercepted UserNameIdentityTokens could have been replayed.