GHSA-jjjj-jwhf-8rgr
HIGHMinIO is Vulnerable to Privilege Escalation via Session Policy Bypass in Service Accounts and STS
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/minio/minioReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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
- An administrator creates a service account or STS account with a restricted inline policy (e.g., access only to bucket1 and bucket2)
- The restricted account attempts to create a new service account for itself without specifying any policy restrictions
- Due to the bypass, the new service account is created with full parent privileges instead of being restricted by the inline policy
- The attacker now has escalated privileges beyond the intended restrictions
Impact
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
Patches
Fixed in PR https://github.com/minio/minio/pull/21642 Commit: c1a49490c78e9c3ebcad86ba0662319138ace190
Install the release
go install -v github.com/minio/[email protected]
Workarounds
No workarounds available. You can upgrade to the latest version immediately.
Mitigation Steps
- Upgrade MinIO: Update to the latest version containing the fix
- Audit Service Accounts: Review all service accounts created by non-admin accounts
- Revoke Suspicious Accounts: Delete any service accounts that may have been created through exploitation
- 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)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/minio/minio | all versions | 0.0.0-20251015170045-c1a49490c78e |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/minio/minio. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/minio/minio to 0.0.0-20251015170045-c1a49490c78e or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jjjj-jwhf-8rgr is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-jjjj-jwhf-8rgr is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-jjjj-jwhf-8rgr. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-jjjj-jwhf-8rgr in your dependencies?
O3 detects GHSA-jjjj-jwhf-8rgr across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.