CVE-2026-82438 Apache Storm Webapp: Authenticated API Responses Exposed to Arbitrary Web Origins
Authenticated Storm users can have cluster and log data read by malicious websites due to insecure CORS and JSONP configurations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-82438?
CVE-2026-82438 is a high-severity vulnerability in Apache Storm Webapp, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-82438?
How do I fix CVE-2026-82438?
No fix has been published for CVE-2026-82438 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-82438 being exploited?
There is no known exploitation of CVE-2026-82438 in the wild and no public exploit code.
Sources
Also known as GHSA-xf44-6rjp-v8cm.