CVE-2026-50222 Overview
CVE-2026-50222 is a missing authorization vulnerability in Apache CloudStack's userdata reference APIs. Several userdata-related endpoints fail to properly validate access control, enabling cross-tenant and cross-account access to userdata resources belonging to other tenants. The affected APIs include deleteUserData, linkUserDataToTemplate, resetUserDataForVirtualMachine, deployVirtualMachine, and updateVirtualMachine. The deleteCniConfiguration API introduced in 4.21.0.0 exhibits the same flaw. The vulnerability is classified under [CWE-200] as exposure of sensitive information to an unauthorized actor.
Critical Impact
Authenticated users in one tenant can access, reference, or manipulate userdata resources owned by other tenants across a shared CloudStack deployment.
Affected Products
- Apache CloudStack 4.18.0.0 through 4.20.3.0
- Apache CloudStack 4.21.0.0 through 4.22.1.0
- deleteCniConfiguration API introduced in 4.21.0.0
Discovery Timeline
- 2026-08-21 - CVE-2026-50222 published to NVD
- 2026-08-27 - Last updated in NVD database
Technical Details for CVE-2026-50222
Vulnerability Analysis
Apache CloudStack exposes a set of userdata reference APIs used to manage instance provisioning metadata. Userdata objects typically contain sensitive configuration such as bootstrap scripts, cloud-init directives, secrets, and application configuration. In a multi-tenant CloudStack deployment, each userdata record must be scoped to its owning account and domain.
The affected endpoints do not consistently enforce ownership validation before performing operations on userdata resources referenced by identifier. An authenticated user in one account can supply a userdata identifier belonging to another tenant and invoke operations such as delete, link-to-template, reset, deploy, or update. This produces cross-tenant information exposure and, in operational terms, allows unauthorized reference to another tenant's provisioning secrets.
Root Cause
The root cause is missing or insufficient access control validation in the userdata reference path of the affected APIs. The APIs accept a userdata identifier as a parameter but do not verify that the caller's account or domain owns the referenced resource before granting access. This is a classic broken access control pattern where authentication is enforced but authorization is not.
Attack Vector
Exploitation requires network access to the CloudStack management API and a valid authenticated session in any tenant. An attacker enumerates or guesses userdata identifiers and issues API requests such as deployVirtualMachine or linkUserDataToTemplate referencing another tenant's userdata. No user interaction or elevated privileges are required. The impact is confidentiality loss of tenant-owned userdata; integrity and availability of the CloudStack platform itself are not directly affected.
No public proof-of-concept exploit is currently available. See the Apache Mailing List Discussion for advisory details.
Detection Methods for CVE-2026-50222
Indicators of Compromise
- API calls to deleteUserData, linkUserDataToTemplate, resetUserDataForVirtualMachine, deployVirtualMachine, or updateVirtualMachine where the referenced userdata ID does not belong to the caller's account or domain.
- Unusual enumeration patterns against userdata identifiers from a single tenant account.
- deleteCniConfiguration calls referencing CNI configurations owned by other tenants on CloudStack 4.21.0.0 and later.
Detection Strategies
- Correlate CloudStack management server audit logs with account and domain ownership records to flag any API request where the requesting account differs from the userdata owner.
- Alert on high-volume userdata reference API calls from a single account within short time windows, indicative of identifier enumeration.
- Review virtual machine deploy and update events for userdata references that cross account boundaries.
Monitoring Recommendations
- Enable verbose API auditing on the CloudStack management server and forward logs to a centralized SIEM for cross-tenant correlation.
- Baseline normal userdata API usage per tenant and alert on statistical deviations.
- Monitor upgrade status of all CloudStack management nodes to confirm fixed versions are deployed.
How to Mitigate CVE-2026-50222
Immediate Actions Required
- Upgrade Apache CloudStack to version 4.20.3.1, 4.22.1.1, or later as recommended by the Apache CloudStack project.
- Inventory all CloudStack deployments and identify management servers running affected versions between 4.18.0.0 and 4.22.1.0.
- Audit historical management server logs for suspicious cross-tenant userdata references prior to patching.
- Rotate any secrets, tokens, or credentials embedded in userdata records if cross-tenant access is suspected.
Patch Information
The Apache CloudStack project has released fixed versions 4.20.3.1 and 4.22.1.1 that add proper access control validation to the affected userdata reference APIs and the deleteCniConfiguration API. Details are published in the Apache Mailing List Discussion.
Workarounds
- Restrict CloudStack management API access to trusted administrative networks until patching is complete.
- Temporarily disable or gate userdata management API access for non-administrative accounts using role-based API access controls.
- Avoid storing high-value secrets in CloudStack userdata; use an external secrets manager referenced at boot time instead.
# Verify installed CloudStack version on management server
rpm -qa | grep cloudstack-management
# or on Debian/Ubuntu
dpkg -l | grep cloudstack-management
# After upgrading, confirm fixed version
cloudstack-setup-management --version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
