Auth bypass in Minio

CVE-2026-34204

MinIO is a high-performance object storage system. Prior to version RELEASE.2026-03-26T21-24-40Z, a flaw in extractMetadataFromMime() allows any authenticated user with s3:PutObject permission to inject internal server-side encryption metadata into objects by sending crafted X-Minio-Replication-* headers on a normal PutObject request. This issue has been patched in version RELEASE.2026-03-26T21-24-40Z.

Vulnerability class: Broken Authentication

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H.

EPSS exploit prediction

EPSS: 0.002 (9.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 10th percentile — 9.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-34204: held from 0.001 to 0.002.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.001

Affected products

  • Minio — versions < RELEASE.2026-03-26T21-24-40Z

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-34204?
CVE-2026-34204 is a high-severity vulnerability in Minio, classified under Improper Authentication. CVSS score: 7.1/10. Published 2026-03-31.
How severe is CVE-2026-34204?
High severity. CVSS v3 base score is 7.1 out of 10.