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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-82427 being exploited?
There is no known exploitation of CVE-2026-82427 in the wild and no public exploit code.
Sources
Also known as GHSA-mmm4-x298-c649.