# CVE-2026-82427: Apache Storm Nimbus: Path Traversal as the Supervisor User via Unsanitised Blobstore Map Local Name

> A submitter can exploit path traversal in blobstore mapping to delete files and plant symlinks, enabling code execution as another user when worker isolation is enabled.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-mmm4-x298-c649

## What is CVE-2026-82427?

CVE-2026-82427 is a high-severity path traversal vulnerability in Apache Storm Nimbus, published on 14 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Description

A topology's `topology.blobstore.map` lets the submitter choose a local name for each blob that the
supervisor localises. That name was used to build a path under the topology's working directory without
normalisation, in both `AsyncLocalizer` and `Container.createBlobstoreLinks`, and the symlink helper
force-deletes whatever already exists at the target before creating the link.

A submitter could therefore use `../` segments to direct that delete-and-symlink operation at an arbitrary
path, as the supervisor user, on every node the topology is scheduled onto. The consequences include
recursive deletion of supervisor-owned content and planting a symlink that causes a subsequent worker
launch to execute attacker-chosen code as another tenant's operating-system user, which defeats the
isolation that `supervisor.run.worker.as.user` is intended to provide.

Mitigation

Upgrade to 3.1.0, where the resolved target must lie inside the expected root at both call sites.

Users who cannot upgrade immediately should restrict topology submission to trusted principals, and may
reject submissions whose `topology.blobstore.map` entries contain path separators or `..` segments before
they reach Nimbus.

Credit

The ASF -- found 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-2026-82427?


## How do I fix CVE-2026-82427?

No fix has been published for CVE-2026-82427 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-82427 being exploited?

There is no known exploitation of CVE-2026-82427 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82427 and fix it if it is affected.

What it is: CVE-2026-82427 is a high-severity path traversal vulnerability in Apache Storm Nimbus, published on 14 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-82427 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-2026-82427/ (Markdown: https://insights.sbomify.com/CVE-2026-82427/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82427
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82427
- OSV: https://osv.dev/vulnerability/CVE-2026-82427

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82427/
Summaries are generated and may contain mistakes; the official description above is the record.