MinIO has JWT Algorithm Confusion in OIDC Authentication

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-33322: 0.43% estimated exploitation activity in the next 30 days; percentile 36.88 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact What kind of vulnerability is it? Who is impacted? A JWT algorithm confusion vulnerability in MinIO's OpenID Connect authentication allows an attacker who knows the OIDC ClientSecret to forge arbitrary identity tokens and obtain S3 credentials with any policy, including consoleAdmin. An attacker with knowledge of the OIDC ClientSecret can: - Impersonate any user identity - Obtain S3 credentials with any IAM policy, including consoleAdmin - Access, modify, or delete any data in the MinIO deployment The attack is deterministic (100% success rate, no race conditions). Attack Prerequisites The attacker must know the OIDC ClientSecret. While this is a shared credential (not a private key), it is more accessible than commonly assumed: - CVE-2023-28432 previously leaked environment variables including MINIOIDENTITYOPENIDCLIENTSECRET - Client secrets are often present in frontend OAuth configurations, mobile app bundles, CI/CD pipelines, and shared configuration files - In many…

Published by the source

19 Mar 2026, 17:56 UTC

Last modified by the source

27 Mar 2026, 21:57 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5cx5-wh4m-82fh

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# Patch Next advisory brief: CVE-2026-33322

Advisory: MinIO has JWT Algorithm Confusion in OIDC Authentication
IDs: CVE-2026-33322, GHSA-5cx5-wh4m-82fh
Record: https://patchnext.com/advisories/cve-2026-33322 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/minio/minio: affected <= 0.0.0-20260212201848-7aac2a2c5b7c

## Suggested inspection (read-only)
- Go github.com/minio/minio: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/minio/minio.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5cx5-wh4m-82fh (GitHub-reviewed advisory GHSA-5cx5-wh4m-82fh lists affected ranges: Go github.com/minio/minio >=0 <=0.0.0-20260212201848-7aac2a2c5b7c)

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