CVE-2026-39360

moderate-risk

Published 2026-04-07

RustFS is a distributed object storage system built in Rust. Prior to alpha.90, RustFS contains a missing authorization check in the multipart copy path (UploadPartCopy). 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 breaks tenant isolation in multi-user / multi-tenant deployments. This vulnerability is fixed in alpha.90.

Do I need to act?

0.03% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 4.3/10 Medium

NETWORK / LOW complexity

Affected Products (20)

Rustfs

Affected Vendors

Rustfs

References (1)

Exploit https://github.com/rustfs/rustfs/security/advisories/GHSA-mx42-j6wv-px98

/ 100

moderate-risk

Severity 18/34 · Moderate

Exploitability 0/34 · Minimal

Exposure 29/34 · Critical