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Critical

JWT algorithm confusion in MinIO OpenID Connect authentication

IdentifiersCVE-2026-33322CWE-287· Improper Authentication

CVE-2026-33322 is a JWT algorithm confusion vulnerability in MinIO's OpenID Connect authentication implementation. It affects MinIO releases from RELEASE.2022-11-08T05-27-07Z up to, but not including, RELEASE.2026-03-17T21-25-16Z. The flaw allows an attacker who knows the configured OIDC ClientSecret to forge arbitrary identity tokens. By presenting forged tokens, the attacker can cause MinIO to issue S3 credentials associated with attacker-chosen policies, including the highly privileged consoleAdmin policy. This is an authentication failure in the OIDC token validation path that results in acceptance of attacker-controlled identity assertions.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation results in full authentication bypass within the affected OIDC trust boundary. An attacker can mint arbitrary identities and obtain valid MinIO S3 credentials with any policy they choose, including consoleAdmin. This can lead to complete compromise of the MinIO deployment, including unauthorized access to stored objects, modification or deletion of data, administrative control through privileged policies, and broad impact to confidentiality, integrity, and availability.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by disabling or restricting MinIO OIDC authentication where operationally feasible, limiting access to MinIO endpoints, and tightly protecting the OIDC ClientSecret. Restrict who can read configuration or secret material, rotate the ClientSecret if compromise is suspected, and monitor for anomalous token-based logins or issuance of unexpected high-privilege S3 credentials. These are temporary risk-reduction measures only; the definitive fix is to upgrade to a patched release.

Remediation

Patch, then assume compromise.

Upgrade MinIO to RELEASE.2026-03-17T21-25-16Z or later, which contains the vendor patch for this issue. Because exploitation requires knowledge of the OIDC ClientSecret and may result in issuance of highly privileged credentials, rotate the OIDC ClientSecret after patching and invalidate or review any issued credentials, sessions, and related trust relationships as appropriate. Review audit logs for suspicious OIDC authentications and unexpected issuance of high-privilege policies such as consoleAdmin.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
MinioMinioapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

2 SOURCESView more in app
What this page doesn’t show

The version that knows your environment.

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-33322
NVD
nvd.nist.gov/vuln/detail/CVE-2026-33322
MITRE CWE · CWE-287
Improper Authentication
Vendor Advisory
github.com/minio/minio/security/advisories/GHSA-5cx5-wh4m-82fh