CVE-2026-82432

/// Technical 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

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References