CVE-2026-54155 is a high-severity (CVSS 7.7) CWE-347 vulnerability in node-opcua. No vendor fix is recorded yet; mitigation options are listed below.
node-opcua: Missing nonce verification in UserNameIdentityToken authentication
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54155.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-54155 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 382,621 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
node-opcuanpmDescription
Summary A missing nonce verification in the UserNameIdentityToken authentication handler allows an unauthenticated remote attacker to forge a password token that extracts as an empty string, and to replay captured authentication tokens across sessions.
Affected versions: <= 2.165.0 Tested version: 2.165.0 CVSS Score: 8.1 (High) CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L CWE: CWE-347 Improper Verification of Cryptographic Signature
Root Cause
In packages/node-opcua-server/source/opcua_server.ts at line 1886-1887, after RSA-OAEP decrypting the UserNameIdentityToken password blob, the server reads a 4-byte little-endian length field and extracts buff[4 : 4+length] as the password. It never verifies that the trailing bytes equal session.nonce.
This has two consequences:
-
Forged empty password: An attacker who retrieves the server's public key via an unauthenticated
GetEndpointscall can craft a token where the 4-byte length field equalsserverNonce.length(32). The server computeslength = 32 - 32 = 0and callsisValidUser(username, ""). Any account that accepts an empty password is compromised. -
Unconditional replay attack: Because nonce binding is structurally absent, any captured UserNameIdentityToken ciphertext can be replayed in a different session unconditionally.
The impact is compounded by a second issue: when the channel uses SecurityMode=None, verifyClientSignature returns true unconditionally (security_policy.ts:697-700), bypassing the channel-level signature check entirely.
Proof of Concept (logic, no exploit code)
1. GetEndpoints (unauthenticated) → retrieve server public key and RSA token policy
2. OpenSecureChannel (SecurityMode=None)
3. CreateSession
4. Craft plaintext: [0x20, 0x00, 0x00, 0x00] (readUInt32LE = 32 = serverNonce.length)
5. RSA-OAEP encrypt with server public key → 256-byte ciphertext
6. ActivateSession with crafted UserNameIdentityToken
7. Server decrypts → length = 32 - 32 = 0 → password = ""
8. isValidUser(username, "") is called
Dynamically confirmed: decryption produces password = "" with no error and no nonce verification.
Suggested Fix
After decrypting the password blob, verify that buff.slice(4 + passwordLength) equals session.nonce before extracting the password. Reject the token if verification fails.
I am following a 90-day responsible disclosure policy. I am happy to provide additional technical details under embargo. Please confirm receipt at your earliest convenience.
Reporter: Stanley Tobias Discovery date: 2026-03-23
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | node-opcua | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for node-opcua, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of node-opcua has shipped for CVE-2026-54155 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-54155 in your dependencies?
Find it across npm, including transitive dependencies.