# CVE-2026-69200: node-opcua: Prototype Pollution via internal `fieldsToJson()` implementation (Related to CVE-2024-57086)

> Prototype pollution in node-opcua allows attackers to corrupt application logic or cause denial of service via unsanitized field names.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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:** 16 Sep 2026
- **Updated:** 18 Sep 2026
- **Also known as:** GHSA-cv5q-7543-48q4

## What is CVE-2026-69200?

CVE-2026-69200 is a low-severity vulnerability in node-opcua, published on 16 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 node-opcua-client 2.145.0, the internal fieldsToJson method in packages/node-opcua-client/source/alarms_and_conditions/client_alarm.ts directly assigns unsanitized field names and allows a __proto__.pollutedKey path to modify Object.prototype. Successful exploitation requires an application to expose attacker-controlled event fields to fieldsToJson and may cause denial of service or application logic corruption. This vulnerability is fixed in 2.145.0.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-69200?


## How do I fix CVE-2026-69200?

No fix has been published for CVE-2026-69200 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-69200 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-69200 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-69200 and fix it if it is affected.

What it is: CVE-2026-69200 is a low-severity vulnerability in node-opcua, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-69200 exists.

Affected product: node-opcua. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-69200/ (Markdown: https://insights.sbomify.com/CVE-2026-69200/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-69200
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-69200
- OSV: https://osv.dev/vulnerability/CVE-2026-69200

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-69200/
Summaries are generated and may contain mistakes; the official description above is the record.