CVE-2026-82440

HIGHCVSS 8.1/10EPSS 0.25%

Last modified

CVE-2026-82440 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. 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. EPSS estimates a 0.25% chance of exploitation in the next 30 days.

Description

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.

Metrics

EPSS Probability
0.25%

16.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
Apache Software FoundationApache Storm Nimbus>= 3.0.0, < 3.1.0

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-82440?
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.
How severe is CVE-2026-82440?
CVE-2026-82440 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.
How do I fix CVE-2026-82440?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST