CVE-2026-82440Apache Storm Nimbus unsafe reflection
CVE-2026-82440 is a unsafe reflection in Apache Storm Nimbus, not yet scored.
Why this priority: Not scored yet, and no exploitation signal.
Published · Updated · NVD status: Received
What it is
Input picks which class or method the application loads.
How it is reached
The record does not say yet how the flaw is reached; the description below is the best guide until it is scored.
What an attacker gains
Its impact has not been scored yet. In practice, this kind of flaw lets an attacker run commands or code with the privileges of the affected service.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Upgrade Apache Storm Nimbus to 3.1.0 or later.
Description from NVD
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.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Application servers and the hosts they run on. The flaw sits between untrusted input and code or command execution.
- Template engines. The flaw sits between untrusted input and code or command execution.
Trust boundaries in play
- Between untrusted input and code or command execution. An attacker who crosses it can run commands or code with the privileges of the affected service.
Questions to answer about your own systems
- Where does Apache Storm Nimbus run in your systems, and at which version?
- Which of those instances are reachable by people you do not trust?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.