CVE-2026-39360 rustfs CVE debrief

Who should care

Users of RustFS, especially those with multi-user or multi-tenant deployments, should be aware of this vulnerability and take steps to mitigate it. This includes upgrading to alpha.90 or later and reviewing access controls for the affected system. Operators, platform administrators, vulnerability management teams, and security teams may be impacted.

Technical summary

The vulnerability exists in the multipart copy path (UploadPartCopy) of RustFS, a distributed object storage system built in Rust. A low-privileged user who cannot read objects from a victim bucket can still exfiltrate victim objects by copying them into an attacker-controlled multipart upload and completing the upload. This is due to a missing authorization check. The vulnerability has a CVSS score of 5.3 and a severity of MEDIUM. It affects multi-user / multi-tenant deployments, breaking tenant isolation.

Defensive priority

Medium priority should be given to patching or mitigating this vulnerability, especially in multi-user or multi-tenant environments.

Recommended defensive actions

• Upgrade to alpha.90 or later
• Review and adjust access controls for the affected system
• Monitor for suspicious activity related to multipart uploads
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE record was published on 2026-04-07T19:16:46.673Z and has not been modified since then. The NVD entry is currently Analyzed. This information is based on the provided source corpus. Further verification by defenders is recommended to ensure accuracy and completeness of the information.

Official resources