---
id: "CVE-2026-82440"
page: "https://infrastack.ai/live/CVE-2026-82440"
kind: "vulnerability"
aliases: ["CVE-2026-82440"]
title: "Apache Storm: Nimbus instantiates any class named in topology scheduler strategy"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["apache-storm", "nimbus", "package", "self-hosted"]
not_affected_if: ["auth-required", "explicit-whitelist"]
published_at: "2026-11-09T10:17:11+00:00"
first_seen_at: "2026-11-09T10:25:49+00:00"
updated_at: "2026-11-09T10:26:35+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82440", "first_seen_at": "2026-11-09T10:25:49+00:00"}]
exploit_sources: []
---

# Apache Storm: Nimbus instantiates any class named in topology scheduler strategy

Link for people: https://infrastack.ai/live/CVE-2026-82440 (this .md is for agents)

When the scheduler strategy allowlist is unset, Nimbus instantiates any no-argument class on its classpath when a topology is scheduled. An authenticated submitter can use this to start side-effecting classes such as InProcessZookeeper and exhaust threads, sockets and memory in the Nimbus daemon.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Storm version in use with `storm version`; affected versions are those before `3.1.0`.
- Check whether `nimbus.scheduler.strategy.class.whitelist` is set in `storm.yaml` or the Nimbus configuration; if it is unset, the cluster is in the shipped state the advisory describes.

## Fix

- Apache Storm: upgrade to `3.1.0`, where an unset allowlist means the strategies shipped with Storm.
- Until upgraded: set `nimbus.scheduler.strategy.class.whitelist` explicitly to the strategies intended to be permitted.

## Timeline

- 2026-11-09T10:25:49+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-82440

## From the sources

Description

Nimbus instantiates the class named by a topology's `topology.scheduler.strategy` when scheduling it. The
allowlist intended to constrain that choice, `nimbus.scheduler.strategy.class.whitelist`, was treated as
"allow any class" when unset, and it had no entry in the shipped `defaults.yaml`, so unset was the shipped
state. An authenticated submitter could therefore cause Nimbus to instantiate any class on the Nimbus
classpath that has a no-argument constructor.

Storm's own production artifacts contain classes with side effects suitable for this: instantiating
`org.apache.storm.testing.InProcessZookeeper` starts a ZooKeeper server with its own threads and sockets
and nothing closes it, and `org.apache.storm.LocalCluster` behaves similarly. Repeated submissions
therefore consume threads, sockets and memory in the most privileged daemon in the cluster.

Mitigation

Upgrade to 3.1.0, where an unset allowlist means the strategies shipped with Storm rather than any class.

Note that this is a behaviour change: a cluster running an out-of-tree scheduler strategy without an
explicit allowlist will have those topologies refused until the class is added to
`nimbus.scheduler.strategy.class.whitelist`. The rejection message names the refused class and the
configuration key.

Users who cannot upgrade immediately should set `nimbus.scheduler.strategy.class.whitelist` explicitly to
the strategies they intend to permit.

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