CVE-2013-6437 in Compute
Summary
by MITRE
The libvirt driver in OpenStack Compute (Nova) before 2013.2.2 and icehouse before icehouse-2 allows remote authenticated users to cause a denial of service (disk consumption) by creating and deleting instances with unique os_type settings, which triggers the creation of a new ephemeral disk backing file.
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Analysis
by VulDB Data Team • 05/07/2026
The vulnerability described in CVE-2013-6437 represents a significant denial of service weakness within the OpenStack Compute (Nova) platform that specifically affects the libvirt driver component. This flaw exists in versions of Nova prior to 2013.2.2 and the icehouse release, creating a persistent resource exhaustion threat that can be exploited by authenticated attackers. The vulnerability operates through a sophisticated mechanism involving the manipulation of operating system type configurations during instance creation processes, which directly impacts the underlying storage infrastructure of the cloud environment.
The technical exploitation of this vulnerability relies on the fundamental design flaw in how Nova handles ephemeral disk backing file creation when instances are provisioned with unique os_type parameters. When an authenticated user creates and subsequently deletes instances using distinct os_type settings, the system generates new backing files for each unique configuration without proper cleanup mechanisms. This creates a cascading effect where each instance deletion does not properly reclaim the associated storage resources, leading to progressive disk space exhaustion. The flaw operates at the storage layer where Nova's libvirt driver maintains separate backing files for different operating system configurations, creating a persistent resource leak that can be systematically exploited.
From an operational impact perspective, this vulnerability presents a severe threat to cloud infrastructure stability and availability. The denial of service condition manifests as progressive disk consumption that can ultimately render the entire compute node incapable of hosting new instances or performing normal operations. Attackers can systematically consume available disk space by repeatedly creating and deleting instances with unique os_type values, effectively causing a resource exhaustion attack that affects not only individual virtual machines but potentially entire compute hosts. The impact extends beyond simple service disruption to include potential data loss scenarios and service degradation that can compromise the overall reliability of the cloud platform.
The vulnerability aligns with CWE-400, which categorizes resource exhaustion flaws in software systems, and demonstrates characteristics consistent with the ATT&CK technique T1499.001, specifically the use of resource exhaustion to disrupt services. This vulnerability represents a classic case of inadequate resource management where the system fails to properly implement garbage collection or cleanup mechanisms for dynamically created storage resources. The flaw specifically targets the ephemeral storage management within the Nova architecture, where the system should have implemented proper lifecycle management for backing files but instead allowed persistent resource leaks.
Mitigation strategies for this vulnerability require immediate patching of affected Nova components to versions 2013.2.2 or later, which contain the necessary fixes for proper backing file cleanup. System administrators should implement monitoring solutions that track disk space utilization and alert on unusual consumption patterns that may indicate exploitation attempts. Additionally, implementing rate limiting and resource quotas for instance creation operations can help prevent systematic exploitation of this vulnerability. The fix addresses the root cause by ensuring that backing files are properly cleaned up during instance deletion operations, preventing the accumulation of orphaned storage resources. Organizations should also consider implementing automated cleanup procedures and regular audits of storage resources to identify and remediate any lingering issues from previous exploitation attempts.