LF Edge eKuiper: Self-XSS in External Service Creation

Summary

A Cross-Site Scripting (XSS) vulnerability in external service creation allows an authenticated attacker to inject HTML/script payloads into external service names, which may execute in a user's browser when rendered by administrative web interfaces.

Details

Prior to v2.4.0, external service registration endpoints did not strictly enforce alphanumeric character restrictions on service names. An operator or attacker with API access could register a service using a crafted name containing HTML elements (such as <iframe src="...">). If an administrative web UI rendered the unescaped service name, arbitrary script execution could occur in the context of the user's browser session.

PoC

1. Create an external service JSON definition with a filename containing an XSS payload, e.g. <iframe src="javascript:alert1337">.json inside a ZIP archive.
2. In external service creation, upload the ZIP and provide the matching service name: <iframe src="javascript:alert1337">.
3. Upon service registration, the unescaped name executes when rendered in the UI context.

Impact

Self-XSS / Stored XSS leading to potential session token leakage or unauthorized actions in the context of the affected user's browser session.

Remediation & Patches

• Upgrade to eKuiper >= 2.4.0: Strict alphanumeric identifier validation (validate.ValidateID) is now enforced on all external service creation and update endpoints, rejecting invalid characters.

Workarounds

• Protect eKuiper management endpoints (POST /services) with authentication and network-level firewalls.

Credits

• Reported by Alexey Kosmachev, Bi.Zone (@TheMostKnown)