Koenkk Zigbee2MQTT up to 2.12.0 ExternalJSExtension externalJS.ts ExternalJSExtension.getFilePath Name path traversal

Summaryinfo

A vulnerability classified as critical has been found in Koenkk Zigbee2MQTT up to 2.12.0. The impacted element is the function ExternalJSExtension.getFilePath of the file lib/extension/externalJS.ts of the component ExternalJSExtension. Performing a manipulation of the argument Name results in path traversal. This vulnerability is reported as CVE-2026-71279. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability classified as critical has been found in Koenkk Zigbee2MQTT up to 2.12.0. This affects the function ExternalJSExtension.getFilePath of the file lib/extension/externalJS.ts of the component ExternalJSExtension. The manipulation of the argument name with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Zigbee2MQTT's ExternalJSExtension.getFilePath() (lib/extension/externalJS.ts) joins a `name` 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. Because path.join() resolves `../` sequences, a name such as `../../tmp/evil.js` escapes the intended extensions directory. 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. Requires the `enable_external_js` config option (off by default, but commonly enabled in legacy installs) and MQTT broker access, which is frequently unauthenticated in real deployments. The identical unsanitized getFilePath() is also used by the extension-removal handler, enabling arbitrary file deletion.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-71279 since 08/05/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/05/2026). MITRE ATT&CK project uses the attack technique T1006 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• Koenkk

Name

• Zigbee2MQTT

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12.0

CPE 2.3info

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CPE 2.2info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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