CVE-2026-40344: MinIO is a high-performance object storage system

This month

HIGH 8.2REMOTEUPGRADE

CVE-2026-40344 is a high-severity flaw (CVSS 8.2) affecting minio. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MinIO is a high-performance object storage system. Starting in RELEASE.2023-05-18T00-05-36Z and prior to RELEASE.2026-04-11T03-20-12Z, an authentication bypass vulnerability in MinIO's Snowball auto-extract handler (`PutObjectExtractHandler`) allows any user who knows a valid access key to write arbitrary objects to any bucket without knowing the secret key or providing a valid cryptographic signature. Any MinIO deployment is impacted. The attack

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 64%)
CISA exploited list	No
Weakness	CWE-287, CWE-306
Published	2026-04-22
Last modified	2026-06-17

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

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 01:16 UTCPublished CVE record published
2026-06-17 10:45 UTCUpdated Record last modified

minio minio UPGRADE

Affected: >= 2023-05-18t00-05-36z and < 2026-04-11T03-20-12Z

Fixed in: 2026-04-11T03-20-12Z

Safe to downgrade to: a release before 2023-05-18t00-05-36z

1. Check installed version

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

2. UPGRADE to 2026-04-11T03-20-12Z (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade minio

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade minio

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2023-05-18t00-05-36z (Debian / Ubuntu)

apt-cache madison minio sudo apt install minio=<VERSION_BEFORE_2023-05-18t00-05-36z> sudo apt-mark hold minio

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list minio sudo dnf downgrade minio-<VERSION_BEFORE_2023-05-18t00-05-36z> sudo dnf versionlock add minio

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-2026-40344?

minio: upgrade to 2026-04-11T03-20-12Z. Exact commands for each OS are on this page.

Is CVE-2026-40344 being exploited?

CVE-2026-40344 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-2026-40344 affect?

CVE-2026-40344 affects minio. Severity is high (CVSS 8.2). MinIO is a high-performance object storage system. Starting in RELEASE.2023-05-18T00-05-36Z and prior to RELEASE.2026-04-11T03-20-12Z, an authentication bypass vulnerability in MinIO's Snowball auto-extract handler (`PutObjectExtractHandler

How urgent is CVE-2026-40344?

Priority 43/100. High severity; Remotely exploitable, no login, no user action

Software pages

MinIO vulnerabilities

Related CVEs

CVE-2026-42600 MEDIUM 4.9 UPGRADE MinIO is a high-performance object storage system
CVE-2026-41145 HIGH 8.2 UPGRADE MinIO is a high-performance object storage system

References

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