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CVE-2026-34204

HIGH

CVE-2026-34204 is a high-severity (CVSS 7.1) Improper Authentication vulnerability in minio minio. O3 Security detects and blocks CVE-2026-34204 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.

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…

Published
Mar 31, 2026
Updated
Jul 24, 2026
Affected
0 pkgs
Patched
None yet
Exploits
None indexed

Description

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.

Affected Products

1 product · 1 configurations
Application
miniominio
< 2026-03-26t21-24-40z
range

Detection & mitigation playbook

Vendor / appliance
  1. Detect

    Inventory every minio minio deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

  2. Fix

    Apply the minio minio security patch or hotfix for CVE-2026-34204 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

  4. How O3 protects you

    O3 detects and blocks CVE-2026-34204 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2026-34204. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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.
O3 Security · Runtime Protection

Is CVE-2026-34204 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-34204 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.