CVE-2026-82438

Description

Three separate mechanisms allowed a web page on an unrelated origin to read responses that Storm's HTTP components served to an authenticated user.

The Logviewer reflected the request's Origin header back in Access-Control-Allow-Origin while also sending Access-Control-Allow-Credentials: true. The published security model documents a permissive Access-Control-Allow-Origin: * posture as accepted, which is safe precisely because browsers refuse to honour * together with credentials; reflecting the concrete origin removes that protection.

The shared CORS filter used by the UI, the Logviewer and DRPC was configured with a response header name where an initialisation parameter name was expected. The container ignored the setting and applied its own defaults, which allow credentials.

Finally, the UI and Logviewer wrapped API responses in a caller-supplied JSONP callback for every GET request. A script element on any origin can load such a response, which bypasses the same-origin policy entirely rather than negotiating it, and there was no way to turn the behaviour off.

In each case the effect is that a page visited by an authenticated operator can read cluster, topology and log data on their behalf.

Mitigation

Upgrade to 3.1.0, where the Logviewer no longer reflects the request origin in a credentialed response, the CORS filter is configured explicitly, and JSONP wrapping is governed by ui.enable.jsonp, which defaults to false.

Note that disabling JSONP is a behaviour change for tooling that passes a callback query parameter; such tooling should be moved to ordinary JSON requests.

Users who cannot upgrade immediately should place the UI, Logviewer and DRPC HTTP endpoints behind a reverse proxy that strips Access-Control-Allow-Origin and Access-Control-Allow-Credentials from responses and rejects requests carrying a callback parameter.

Credit

The ASF -- found using Claude agents to study the security of open-source projects, validated and reported by Apache Storm.