Security Resilience

CVE-2023-28434

Minio ≤ 2023-03-20t20-16-18z

CISA KEVActive ExploitationEUVD ExploitedPublic PoC
Published
22 March 2023
Modified
26 February 2026
KEV Added
19 September 2023
Patch / advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.079 95th percentile
Risk Priority 90 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-28434 is a high-severity Improper Privilege Management (CWE-269) vulnerability in Minio Minio. Its CVSS base score is 8.8 (High).

Operationally, ranked in the top 5% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

MinIO, a multi-cloud object storage framework, contains an authorization bypass vulnerability in versions prior to RELEASE.2023-03-20T20-16-18Z. The flaw lies in the handling of PostPolicyBucket requests, where crafted input can evade metadata bucket-name validation checks and allow object placement into arbitrary buckets. The issue is tracked under CWE-269 and carries a CVSS 3.1 score of 8.8.

An attacker who possesses credentials granting arn:aws:s3:::* permissions and who can reach an instance with Console API access enabled can exploit the weakness to write objects into any bucket on the target deployment. This effectively grants unauthorized write access across the object store without requiring additional privileges beyond the stated policy and API exposure.

The official MinIO advisory and accompanying patches recommend upgrading to RELEASE.2023-03-20T20-16-18Z. As a temporary workaround, operators can enable browser API access while setting MINIO_BROWSER=off to block the affected code path.

The associated EPSS score sits at 0.5209 with no material increase after disclosure.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

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…

more

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`.

CWE(s)
KEV Date Added
19 September 2023

Related Threats

CVEs Like This One

CVE-2024-24747Same product: Minio Minio
CVE-2023-27589Same product: Minio Minio
CVE-2023-28432Same product: Minio Minioboth on KEV
CVE-2026-39414Same product: Minio Minio
CVE-2026-33322Same product: Minio Minio
CVE-2026-34204Same product: Minio Minio
CVE-2026-33419Same product: Minio Minio
CVE-2026-40344Same product: Minio Minio
CVE-2026-42600Same product: Minio Minio
CVE-2026-41145Same product: Minio Minio

Affected Assets

minio
minio
≤ 2023-03-20t20-16-18z

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-269

Policy addresses roles, responsibilities, and privilege management to prevent improper privilege assignments.

addresses: CWE-269

Access supervision ensures privileges are assigned and managed without improper escalation or retention.

addresses: CWE-269

Assigning group/role memberships and access authorizations (privileges) while reviewing accounts addresses improper privilege management.

addresses: CWE-269

Enforces proper privilege management by requiring all decisions through the verified reference monitor.

addresses: CWE-269

By mandating division of duties across roles, the control enforces proper privilege management and prevents a single entity from controlling an entire sensitive process.

addresses: CWE-269

Implements core proper privilege management by restricting to only required rights.

addresses: CWE-269

Policy requires training on privilege management and least privilege, making it harder to exploit improper privilege management weaknesses.

addresses: CWE-269

Training covers proper privilege management practices, making incorrect privilege assignments less likely.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

blocks

A.5.15 directly mandates determining access requirements, defining/enforcing topic-specific access control policy, assigning rights/restrictions by entity/role, consistency with classification, need-to-know, privileged access restrictions, segregation, formal authorization, and dynamic rules — which stops most improper privilege management from being exploitable; bounded remainder is flawed implementation of those rules (e.g. incorrect mapping or enforcement bugs).

blocks

A.5.18 directly governs the provisioning, review, modification and timely revocation of access rights (including for role changes, termination and privilege levels), which stops most improper privilege spheres from being exploitable even if the assignment flaw exists; the bounded remainder is flaws in the underlying enforcement mechanism itself (e.g. AC-3/A.8.3)

blocks

Defining and communicating authorization levels for each role limits the assignment of excessive or unnecessary privileges.

A.8.15 Logging partial match
finds

Logging every use of privileges and protecting those records makes it harder for an attacker who has obtained elevated rights to operate without leaving evidence.

blocks

A.8.2 directly controls the identification, allocation, review, expiry, temporary use, and separation of privileged rights per policy, which prevents most improper privilege management (CWE-269) by design; the bounded remainder is flawed tracking/checking logic inside the product's own enforcement code (the AC-3 slice of 269).

blocks

A.8.27 mandates security-by-design principles including least privilege, default deny, fail securely, defence in depth, security architecture integration, hardening, and zero-trust verification of every request; these directly stop most improper privilege spheres from being exploitable even if the assignment flaw remains, with a bounded remainder (e.g. certain legacy or safety-overridden controls).

Hardening callouts derived

DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.

References