CVE-2025-69233 Overview
CVE-2025-69233 is a time-of-check time-of-use (TOCTOU) race condition vulnerability in Apache CloudStack. The flaw exists in the resource count check and increment logic, where multiple concurrent requests can bypass allocation limits enforced on accounts and domains. Missing validations compound the issue, allowing authenticated users to provision resources beyond their configured quotas. Attackers can exploit this weakness to exhaust infrastructure capacity and trigger denial of service conditions across the cloud platform. The vulnerability affects Apache CloudStack deployments prior to versions 4.20.3.0 and 4.22.0.1.
Critical Impact
Authenticated users can exceed account and domain allocation limits through concurrent requests, leading to resource exhaustion and denial of service against the CloudStack infrastructure.
Affected Products
- Apache CloudStack versions prior to 4.20.3.0
- Apache CloudStack 4.21.x and 4.22.0 prior to 4.22.0.1
- Multi-tenant CloudStack deployments with resource quota enforcement
Discovery Timeline
- 2026-05-08 - CVE-2025-69233 published to NVD
- 2026-05-09 - Last updated in NVD database
Technical Details for CVE-2025-69233
Vulnerability Analysis
The vulnerability resides in Apache CloudStack's resource accounting subsystem, which enforces per-account and per-domain quotas on resources such as virtual machines, volumes, networks, and IP addresses. The platform first checks whether a requested allocation fits within the configured limit, then increments the counter when the resource is created. This check-then-act sequence is not executed atomically.
When multiple resource creation requests arrive in parallel, each request observes the pre-increment counter state and concludes that allocation is permitted. All requests then proceed to provision resources and increment counters after the fact. The result is that combined allocations exceed the enforced quota. Missing validations in adjacent code paths further allow allocation limits to be bypassed even without race exploitation, classified under [CWE-367].
Root Cause
The root cause is the absence of atomic transactions or proper locking around the resource count verification and increment logic. The check-then-increment pattern lacks synchronization primitives, allowing interleaved execution of concurrent quota validations to produce stale reads of the resource counter.
Attack Vector
An attacker with valid CloudStack credentials issues parallel API calls requesting resource creation, such as virtual machine deployment or volume provisioning. By timing requests to race the check-and-increment window, the attacker bypasses configured account or domain limits. Sustained exploitation depletes physical compute, storage, and network capacity, denying service to other tenants and degrading the overall platform.
The vulnerability requires authenticated access with low privileges. Exploitation does not require user interaction but does demand precise timing, reflected in the high attack complexity.
Detection Methods for CVE-2025-69233
Indicators of Compromise
- Account or domain resource usage exceeding configured allocation limits in the CloudStack management database
- Bursts of concurrent identical API requests from a single account targeting deployVirtualMachine, createVolume, associateIpAddress, or similar provisioning endpoints
- Unexplained infrastructure capacity exhaustion despite quota enforcement appearing intact in the UI
Detection Strategies
- Query the CloudStack database to compare resource_count values against configured resource_limit entries for each account and domain, flagging any overruns
- Analyze management server logs for high-frequency parallel resource creation requests originating from the same API key within short time windows
- Correlate API audit events with hypervisor provisioning telemetry to identify allocations that should have been rejected by quota checks
Monitoring Recommendations
- Enable verbose API logging on CloudStack management servers and forward to a centralized SIEM for anomaly analysis
- Establish baseline rates of resource creation per tenant and alert on sudden spikes of concurrent requests
- Monitor underlying hypervisor and storage utilization for sustained growth disproportionate to expected tenant activity
How to Mitigate CVE-2025-69233
Immediate Actions Required
- Upgrade Apache CloudStack to version 4.20.3.0, 4.22.0.1, or later, which contain the fix for the TOCTOU race condition
- Audit current resource consumption against configured limits and reclaim any over-allocated resources from offending accounts
- Rotate API keys for accounts that exhibit suspicious parallel provisioning patterns
Patch Information
The Apache CloudStack project addressed the issue in versions 4.20.3.0 and 4.22.0.1. Patched releases introduce proper synchronization around resource count verification and add the missing validations identified during remediation. Refer to the Apache Mailing List Discussion and the Openwall OSS Security Notice for vendor guidance.
Workarounds
- Apply stricter API rate limiting per account at the load balancer or API gateway to reduce the feasibility of parallel race exploitation
- Lower configured resource limits temporarily to provide additional buffer against quota overruns until patches are deployed
- Restrict resource provisioning APIs to trusted administrative accounts where business workflow permits
# Verify installed Apache CloudStack version on management server
cloudstack-management --version
# Example: confirm upgrade target version meets the fixed release
# Fixed versions: 4.20.3.0 or 4.22.0.1 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
