CVE-2019-10876 in OpenStack Neutron
Summary
by MITRE
An issue was discovered in OpenStack Neutron 11.x before 11.0.7, 12.x before 12.0.6, and 13.x before 13.0.3. By creating two security groups with separate/overlapping port ranges, an authenticated user may prevent Neutron from being able to configure networks on any compute nodes where those security groups are present, because of an Open vSwitch (OVS) firewall KeyError. All Neutron deployments utilizing neutron-openvswitch-agent are affected.
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Analysis
by VulDB Data Team • 08/27/2023
This vulnerability exists within OpenStack Neutron's handling of security groups in versions prior to the specified patches, specifically affecting releases 11.x before 11.0.7, 12.x before 12.0.6, and 13.x before 13.0.3. The flaw manifests when an authenticated user creates two security groups that contain separate or overlapping port ranges, leading to a critical failure in network configuration operations. The root cause stems from a KeyError exception within the Open vSwitch firewall implementation that occurs during the processing of these security group configurations. This issue directly impacts the neutron-openvswitch-agent component which is responsible for managing Open vSwitch firewall rules on compute nodes, making all deployments utilizing this agent susceptible to the vulnerability.
The technical implementation of this vulnerability involves the improper handling of security group rule processing within the Open vSwitch integration layer. When multiple security groups are created with overlapping or adjacent port ranges, the OVS firewall configuration logic fails to properly resolve the rule conflicts, resulting in a KeyError exception that prevents further network configuration operations. This failure mode represents a classic denial of service condition where legitimate network operations become impossible due to the flawed state management of security group rules. The vulnerability operates at the intersection of network virtualization and security policy enforcement, where the conflict resolution mechanism between security groups breaks down under specific rule configurations. According to CWE classification, this represents a weakness in the design of security policy enforcement mechanisms, specifically CWE-248 Uncaught Exception, where an exception occurs during security group processing and is not properly handled.
The operational impact of this vulnerability is severe and far-reaching for OpenStack deployments. Once exploited, the vulnerability renders the neutron-openvswitch-agent incapable of configuring network rules on affected compute nodes, effectively preventing any network connectivity for instances running on those nodes. This creates a cascading failure effect where network services become unavailable across the entire OpenStack deployment, as compute nodes cannot properly configure their network interfaces. The vulnerability can be exploited by any authenticated user with the ability to create security groups, making it particularly dangerous in multi-tenant environments where unauthorized users might gain access to network management capabilities. The attack requires only the creation of two specific security groups with overlapping port ranges, making it relatively simple to execute while having potentially catastrophic effects on network operations.
Mitigation strategies for this vulnerability involve applying the vendor-provided patches that address the KeyError exception in the OVS firewall implementation. Organizations should immediately upgrade to the patched versions of OpenStack Neutron, specifically versions 11.0.7, 12.0.6, and 13.0.3, to resolve the security flaw. Additionally, administrators should implement strict access controls to limit the ability of untrusted users to create security groups, particularly in multi-tenant environments where such privileges are not necessary for all users. Network administrators should also monitor for unauthorized security group creation activities and implement automated alerts for suspicious configuration patterns. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service attacks, where an attacker leverages a weakness in network infrastructure to disrupt service availability. Organizations should also consider implementing network segmentation and least-privilege access controls to limit the scope of potential exploitation while maintaining operational security monitoring to detect anomalous security group creation patterns.