# CVE-2026-82426: Apache Storm Nimbus: Arbitrary File Read on Nimbus via Unvalidated Uploaded Jar Location

> Authenticated users can read arbitrary server files by submitting malicious paths, potentially exposing keys and escalating privileges to cluster admin.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/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-5wqr-qcf5-76p8

## What is CVE-2026-82426?

CVE-2026-82426 is a medium-severity path traversal vulnerability in Apache Storm Nimbus, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Description

Nimbus accepted the `uploadedJarLocation` argument of `submitTopology` / `submitTopologyWithOpts` as a
server-side path and opened it directly, without checking that it referred to a file the caller had
actually uploaded. The intended flow is that a client first calls `beginFileUpload`, which returns a path
inside the Nimbus inbox, and uploads the jar in chunks to that location; nothing bound submission to that
flow, and the `uploaders` map populated by `beginFileUpload` was never consulted at submit time.

An authenticated user with topology submission rights could therefore submit any path readable by the
Nimbus daemon user as their topology jar. Nimbus copied the file into the topology's jar blob, and the
blob ACL grants the submitting subject read access, so the contents could then be retrieved with the
ordinary blob download RPCs. Candidate targets include the Nimbus Kerberos keytab, Thrift and UI TLS
private keys, and `storm.yaml` with the ZooKeeper authentication payload. Possession of the Nimbus keytab
turns an ordinary tenant into a cluster administrator.

In a deployment configured as the documentation recommends, submission is available to every
authenticated principal when `nimbus.users` is unset, so no elevated privilege is required.

Mitigation

Upgrade to 3.1.0, where the submitted location is canonicalised and must resolve inside the Nimbus inbox.

Users who cannot upgrade immediately should restrict topology submission to trusted principals via
`nimbus.users` or `nimbus.groups`, and should treat any file readable by the Nimbus daemon user as
potentially exposed to submitters: rotate the Nimbus keytab and any TLS private keys or ZooKeeper
credentials reachable from that account. Local mode is unaffected.

Credit

Independently reported to the Apache Storm PMC by n0mi1k, with a proof of concept.

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

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-82426?


## How do I fix CVE-2026-82426?

No fix has been published for CVE-2026-82426 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-82426 being exploited?

There is no known exploitation of CVE-2026-82426 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82426 and fix it if it is affected.

What it is: CVE-2026-82426 is a medium-severity path traversal vulnerability in Apache Storm Nimbus, 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-2026-82426 in the wild and no public exploit code.

Affected product: Apache Storm Nimbus. 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-2026-82426/ (Markdown: https://insights.sbomify.com/CVE-2026-82426/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82426
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82426
- OSV: https://osv.dev/vulnerability/CVE-2026-82426

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82426/
Summaries are generated and may contain mistakes; the official description above is the record.