CVE-2026-82432
Deferred Deferred - Pending Action

Authorization Bypass in Apache Storm Nimbus

Publication date: 2026-09-14

Last updated on: 2026-09-14

Assigner: Apache Software Foundation

Description
Description Nimbus validated `topology.blobstore.map` against the calling subject at submission time only. The rebalance operation accepts configuration overrides and stripped a small set of keys from them, but never re-ran that validation, so a caller authorised to rebalance a topology could introduce a blobstore map entry naming a blob whose ACL does not grant them access. Supervisors localise whatever key the map names, placing the blob's contents into the topology's working directory. The same advisory covers `listBlobs`, which performed no authorization check and passed no subject, unlike the neighbouring `getBlobMeta` and `beginBlobDownload` operations. It therefore returned every key in the blobstore to any caller able to reach the Nimbus Thrift port, which provides the key names that make the above practical. On its own the disclosure is metadata only. Mitigation Upgrade to 3.1.0, where rebalance configuration overrides are validated exactly as submission-time configuration is, against the rebalancing caller, and where `listBlobs` applies the configured authorization. Users who cannot upgrade immediately should restrict rebalance rights to trusted principals, keeping in mind that membership of a topology's `topology.users` or `topology.groups` confers them. Credit The ASF -- found using Claude agents to study the security of open-source projects, validated and reported by Apache Storm.

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Meta Information

Published
2026-09-14
Last Modified
2026-09-14
Generated
2026-09-15
AI Q&A
2026-09-14
EPSS Evaluated
N/A
NVD
CVE-2026-82432
EUVD
EUVD-2026-77523

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
apache storm 3.1.0
apache storm to 3.1.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

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Executive Summary

This vulnerability is an authorization bypass in Apache Storm Nimbus versions 3.0.0 to 3.0.x. It occurs because Nimbus only validated blobstore map configurations at topology submission time but not during rebalance operations. Authorized users could exploit this to introduce blobstore entries pointing to inaccessible blobs. Additionally, the listBlobs operation lacked authorization checks, exposing all blobstore key names to any caller with access to the Nimbus Thrift port.

Detection Guidance

To detect CVE-2026-82432, check Apache Storm Nimbus versions between 3.0.0 and 3.0.x. Verify if unauthorized users can access blobstore keys via the Nimbus Thrift port. Inspect logs for topology rebalancing operations with configuration overrides. Use network monitoring to detect unauthorized blob localization attempts.

Impact Analysis

An attacker with rebalance privileges could access unauthorized blob contents by manipulating the blobstore map during rebalance. The listBlobs flaw could expose metadata about all blobs in the system, aiding further attacks. Unauthorized data exposure or privilege escalation may occur if mitigation steps are not taken.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Exposure of blob metadata via listBlobs may also breach data protection principles. Organizations must mitigate this to maintain compliance with these regulations.

Mitigation Strategies

Upgrade to Apache Storm 3.1.0 or later where rebalance configuration overrides are validated and listBlobs enforces authorization. If immediate upgrade is not possible, restrict rebalance rights to trusted principals and avoid granting topology.users or topology.groups membership to untrusted users.

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