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CVE-2023-28434

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in MinIO. For every flaw being used in attacks, see Exploited flaws.

CVE-2023-28434 is a security flaw in MinIO. Someone who already has a foothold can use MinIO to take full control of the machine. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 19 Sep 2023.[1]

MinIO is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. MinIO has published a fix or advice.

Description

CISA calls it a security feature bypass in MinIO MinIO. In its words: “MinIO contains a security feature bypass vulnerability that allows an attacker to use crafted requests to bypass metadata bucket name checking and put an object into any bucket while processing `PostPolicyBucket` to conduct privilege escalation. To carry out this attack, the attacker requires credentials with `arn:aws:s3:::*` permission, as well as enabled Console API access.”[1]

The CVE record adds: “Minio is a Multi-Cloud Object Storage framework. Prior to RELEASE.2023-03-20T20-16-18Z, an attacker can use crafted requests to bypass metadata bucket name checking and put an object into any bucket while processing `PostPolicyBucket`. To carry out this attack, the attacker requires credentials with `arn:aws:s3:::*` permission, as well as enabled Console API access. This issue has been patched in RELEASE.2023-03-20T20-16-18Z. As a workaround, enable browser API access and turn off `MINIO_BROWSER=off`.”[2]

The underlying weakness is improper privilege management (CWE-269), in MITRE’s list of common software weaknesses.

It scores 8.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record doesn’t list version ranges for it; MinIO’s advisory has them[3]. CISA names the product as MinIO MinIO.

Most families won’t have MinIO; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 19 Sep 2023, 181 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 10 Oct 2023 to fix it.[1]

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 8%. That’s in the top 6% of the flaws it scores.[4]

CISA assesses it as not automatable: each attack takes some work.

CISA doesn’t say who was attacked, or how.

Fix

MinIO has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]

  1. Check whether you use it.MinIO is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 10 Oct 2023 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 8.8.[2]
CISA adds it to its catalog of flaws known to be used in attacks.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at 8%.[4]

See also

Other MinIO flaws

Other improper privilege management flaws

  • CVE-2026-102490, Zammad GmbH Zammad: improper privilege management ·
  • CVE-2026-84869, ConnectWise ScreenConnect: improper privilege management and missing authorization ·
  • CVE-2026-46817, Oracle E-Business Suite: improper privilege management ·
  • CVE-2026-21533, Microsoft Windows: improper privilege management ·
  • CVE-2024-8068, Citrix Session Recording: improper privilege management ·

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “MinIO Security Feature Bypass Vulnerability”. Known Exploited Vulnerabilities Catalog, added 19 Sep 2023.
  2. ^ National Institute of Standards and Technology. “CVE-2023-28434 Detail”. National Vulnerability Database, published 22 Mar 2023.
  3. ^ MinIO. Advisories and fixes: github.com.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.079, percentile 94.7, 31 Oct 2026.
  5. CVE Program. “CVE-2023-28434”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.