CVE-2026-40937: RustFS is a distributed object storage system built in Rust

Routine

HIGH 8.3DOWNGRADE

CVE-2026-40937 is a high-severity flaw (CVSS 8.3) 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 1.0.0-alpha.94, all four notification target admin API endpoints in `rustfs/src/admin/handlers/event.rs` use a `check_permissions` helper that validates authentication only (access key + session token), without performing any admin-action authorization via `validate_admin_request`. Every other admin handler in the codebase correctly calls `validate_admin_request` with a specifi

Why this priority

High severity

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

Risk facts

CVSS score	8.3 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 78%)
CISA exploited list	No
Weakness	CWE-862
Published	2026-04-22
Last modified	2026-06-17

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

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-22 21:17 UTCPublished CVE record published
2026-06-17 10:45 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-2026-40937?

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

Is CVE-2026-40937 being exploited?

CVE-2026-40937 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-2026-40937 affect?

CVE-2026-40937 affects rustfs. Severity is high (CVSS 8.3). RustFS is a distributed object storage system built in Rust. Prior to 1.0.0-alpha.94, all four notification target admin API endpoints in `rustfs/src/admin/handlers/event.rs` use a `check_permissions` helper that validates authentication on

How urgent is CVE-2026-40937?

Priority 34/100. High severity

References

← Back to latest CVEs