# 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.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-xf44-6rjp-v8cm

## 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.

Weakness: CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains), CWE-346 (Origin Validation Error)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82438 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-82438 in the wild and no public exploit code.

Affected product: Apache Storm Webapp. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-82438/ (Markdown: https://insights.sbomify.com/CVE-2026-82438/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82438
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82438
- OSV: https://osv.dev/vulnerability/CVE-2026-82438

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82438/
Summaries are generated and may contain mistakes; the official description above is the record.