CVE-2026-39360: RustFS is a distributed object storage system built in Rust

Routine

MEDIUM 4.3DOWNGRADE

CVE-2026-39360 is a medium-severity flaw (CVSS 4.3) affecting rustfs. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 vulnerabilit

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	4.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 90%)
CISA exploited list	No
Weakness	CWE-862
Published	2026-04-07
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: rustfs

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-07 19:16 UTCPublished CVE record published
2026-07-24 21:10 UTCUpdated Record last modified

rustfs rustfs DOWNGRADE

Affected: 1.0.0 alpha1 · 1.0.0 alpha10 · 1.0.0 alpha11 · 1.0.0 alpha12 · 1.0.0 alpha13 · 1.0.0 alpha14 · 1.0.0 alpha15 · 1.0.0 alpha16

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0.0

1. Check installed version

apt-cache policy rustfs || rpm -q rustfs || rustfs --version

2. No fixed release: DOWNGRADE to a release before 1.0.0 (Debian / Ubuntu)

apt-cache madison rustfs sudo apt install rustfs=<VERSION_BEFORE_1.0.0> sudo apt-mark hold rustfs

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list rustfs sudo dnf downgrade rustfs-<VERSION_BEFORE_1.0.0> sudo dnf versionlock add rustfs

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-39360?

rustfs: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-39360 being exploited?

CVE-2026-39360 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-39360 affect?

CVE-2026-39360 affects rustfs. Severity is medium (CVSS 4.3). 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 ca

How urgent is CVE-2026-39360?

Priority 23/100. Public exploit reference

Related CVEs

CVE-2026-40937 HIGH 8.3 DOWNGRADE RustFS is a distributed object storage system built in Rust

References

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