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Vulnerabilities

Vulnerability · CVE-2026-40344

MinIO is a high-performance object storage system.

Published Apr 22, 2026 · catalog updated Jun 17, 2026 · MinIO is a high-performance

Check if you run it

No confirmed exploitation is on record for CVE-2026-40344. EPSS is 0.71%. Act only if a listed version of MinIO is a high-performance is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (MinIO is a high-performance).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.71%
Remediation
Advisory link
Affected products
cpe minio/minio

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 ( ) 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 requires only a valid access key (the well-known default , or any key with WRITE permission on a bucket) and a target bucket name. When support was added, the new auth type was handled in and but was never added to . The snowball auto-extract handler's block has no case for , so execution falls through with zero signature verification. The call before the switch extracts the access key and checks IAM permissions, but does not verify the cryptographic signature. An attacker sends a PUT request with , , and an header containing a valid access key with a completely fabricated signature. The request is accepted and the tar payload is extracted into the bucket. Users of the open-source minio/minio project should upgrade to MinIO AIStor RELEASE.2026-04-11T03-20-12Z or later. If upgrading is not immediately possible, block unsigned-trailer requests at the load balancer. Reject any request containing X-Amz-Content-Sha256: STREAMING-UNSIGNED-PAYLOAD-TRAILER at the reverse proxy or WAF layer. Clients can use STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER (the signed variant) instead. Alternatively, restrict WRITE permissions. Limit s3:PutObject grants to trusted principals. While this reduces the attack surface, it does not eliminate the vulnerability since any user with WRITE permission can exploit it with only their access key.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe minio/minioversion unspecified

How to fix CVE-2026-40344

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-40344. EPSS is 0.71%. Act only if a listed version of MinIO is a high-performance is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-287: Improper Authentication; CWE-306: Missing Authentication for Critical Function. EPSS 0.71%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 22, 2026 · NIST NVD

    Detected

    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 ( ) 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 deployme

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 ( ) 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 deployme

Sources

  • CVE.orgVulnerability recordCVE-2026-40344

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-40344

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-2026-40344

    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 ( ) allows any user who knows a valid acc

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.