# CVE-2026-54155: node-opcua: Missing nonce verification in UserNameIdentityToken authentication

> An unauthenticated attacker can bypass authentication in node-opcua by forging tokens with empty passwords or replaying captured tokens, leading to account takeover.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-mq36-523m-x7vv

## What is CVE-2026-54155?

CVE-2026-54155 is a high-severity authentication bypass vulnerability in node-opcua, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

node-opcua is an OPC UA implementation for TypeScript and Node.js. Prior to 2.166.0, the UserNameIdentityToken authentication handler in packages/node-opcua-server/source/opcua_server.ts decrypts an RSA-OAEP password blob but does not verify that the trailing bytes match the current session serverNonce. An unauthenticated remote attacker can obtain the server public key through GetEndpoints and forge a blob whose little-endian length produces an empty password passed to isValidUser, compromising accounts that accept an empty password. Missing nonce binding also allows a captured UserNameIdentityToken ciphertext to be replayed in another session, and SecurityMode=None removes the separate client-signature safeguard. This issue is fixed in version 2.166.0.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2026-54155?

2 open source packages ship an affected version, including node-opcua.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `node-opcua` | npm | All versions to 2.165.0 | None |
| `node-opcua` | npm | All versions to 2.165.0 | None |

## How do I fix CVE-2026-54155?

No fix has been published for CVE-2026-54155 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-54155 being exploited?

There is no known exploitation of CVE-2026-54155 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54155 and fix it if it is affected.

What it is: CVE-2026-54155 is a high-severity authentication bypass vulnerability in node-opcua, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-54155 in the wild and no public exploit code.

Affected packages and fixed versions:
- node-opcua (npm): affected all versions up to 2.165.0; no fix listed
- node-opcua (npm): affected all versions up to 2.165.0; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54155/ (Markdown: https://insights.sbomify.com/CVE-2026-54155/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54155
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54155
- OSV: https://osv.dev/vulnerability/CVE-2026-54155

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54155/
Summaries are generated and may contain mistakes; the official description above is the record.