CVE-2025-62506

A privilege escalation vulnerability allows service accounts and STS (Security Token Service) accounts with restricted session policies to bypass their inline policy restrictions when performing "own" account operations, specifically when creating new service accounts for the same user.

Details

The vulnerability exists in the IAM policy validation logic in cmd/iam.go. When validating session policies for restricted accounts performing operations on their own account (such as creating service accounts), the code incorrectly relied on the DenyOnly argument.

The DenyOnly flag is used to allow accounts to perform actions related to their own account by only checking if the action is explicitly denied. However, when a session policy (sub-policy) is present, the system should validate that the action is actually allowed by the session policy, not just that it isn't denied.

Attack Scenario

1. An administrator creates a service account or STS account with a restricted inline policy (e.g., access only to bucket1 and bucket2)
2. The restricted account attempts to create a new service account for itself without specifying any policy restrictions
3. Due to the bypass, the new service account is created with full parent privileges instead of being restricted by the inline policy
4. The attacker now has escalated privileges beyond the intended restrictions

Workarounds

No workarounds available. You can upgrade to the latest version immediately.

Mitigation Steps

1. Upgrade MinIO: Update to the latest version containing the fix
2. Audit Service Accounts: Review all service accounts created by non-admin accounts
3. Revoke Suspicious Accounts: Delete any service accounts that may have been created through exploitation
4. Review Access Logs: Check for unauthorized access to sensitive buckets

Resources

• Fix PR: https://github.com/minio/minio/pull/21642
• Affected code: cmd/iam.go (functions: isAllowedBySessionPolicyForServiceAccount, isAllowedBySessionPolicy)

Attack Complexity: LOW - Exploitation requires only valid credentials for a restricted service/STS account

Confidentiality: HIGH - Attackers can access buckets and objects beyond their intended restrictions

Integrity: HIGH - Attackers can modify, delete, or create objects outside their authorized scope

Availability: NONE - Does not directly impact service availability

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

CVE-2025-62506 has a CVSS score of 8.1 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.0.0-20251015170045-c1a49490c78e); upgrading removes the vulnerable code path.

Kodem intelligence

Fixed in PR https://github.com/minio/minio/pull/21642
Commit: c1a49490c78e9c3ebcad86ba0662319138ace190

Install the release

go install -v github.com/minio/[email protected]

1. What is CVE-2025-62506? CVE-2025-62506 is a high-severity incorrect authorization vulnerability in github.com/minio/minio (go), affecting versions < 0.0.0-20251015170045-c1a49490c78e. It is fixed in 0.0.0-20251015170045-c1a49490c78e. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. How severe is CVE-2025-62506? CVE-2025-62506 has a CVSS score of 8.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/minio/minio are affected by CVE-2025-62506? github.com/minio/minio (go) versions < 0.0.0-20251015170045-c1a49490c78e is affected.
4. Is there a fix for CVE-2025-62506? Yes. CVE-2025-62506 is fixed in 0.0.0-20251015170045-c1a49490c78e. Upgrade to this version or later.
5. Is CVE-2025-62506 exploitable, and should I be worried? Whether CVE-2025-62506 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-62506 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-62506? Upgrade github.com/minio/minio to 0.0.0-20251015170045-c1a49490c78e or later.