# CVE-2026-82431: Apache Storm SimpleACLAuthorizer authorization bypass

Source: https://junglewise.ai/threats/cve-2026-82431-apache-storm-simpleaclauthorizer-authorization-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-14. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-82431 · Severity: critical · CVSS 9.8 · Published 2026-09-14

Apache Storm is a distributed stream processing framework used to ingest and process large volumes of real-time data. A flaw in the authorization system allows any authenticated user to perform restricted administrative operations—including topology submission and configuration access—when cluster access is controlled by group membership alone. This means deployments following the documented security guidance could believe they are protected when they are completely unrestricted.

Technologies: [Apache Storm](https://junglewise.ai/threats/technologies/storm). Vendors: [Apache](https://junglewise.ai/threats/vendors/apache).

## Quick answers

**Is CVE-2026-82431 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-82431 being exploited in the wild.

**How severe is CVE-2026-82431?** Critical severity, with a CVSS score of 9.8, published 14 September 2026.

**Which products and versions are affected?** Apache Storm before 3.1.0.

**Is there a fix for CVE-2026-82431?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-82431 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-82431?** Check whether you run Apache Storm at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an authorization bypass in SimpleACLAuthorizer that returns early when nimbus.users is empty, before evaluating nimbus.groups. This causes group-based access restrictions to be silently ignored, permitting all authenticated principals to execute user-level operations (submitTopology, beginFileUpload, getNimbusConf). The attack requires authentication but no further preconditions; the vulnerability silently bypasses controls documented as a supported restriction mechanism. Patch to version 3.1.0 to fix; affected versions require either upgrading or as a workaround populating nimbus.users to force group evaluation.

## Affected products

- Apache Storm before 3.1.0

## Timeline

- 2026-09-14: disclosed

## Related threats

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- [Apache Storm arbitrary class instantiation in scheduler](https://junglewise.ai/threats/cve-2026-82440-description-nimbus-instantiates-the-class-named-by-a-topology-s)
- [Apache Storm unsafe deserialization in state serialization](https://junglewise.ai/threats/cve-2026-82436-description-defaultstateserializer-used-to-persist-and-restore)
- [Apache Storm CORS misconfiguration allows credential-based data exposure](https://junglewise.ai/threats/cve-2026-82438-apache-storm-cors-misconfiguration-allows-credential-based-data)