CVE-2019-6676 in BIG-IP
Summary
by MITRE
On versions 15.0.0-15.0.1, 14.0.0-14.1.2.2, and 13.1.0-13.1.3.1, TMM may restart on BIG-IP Virtual Edition (VE) when using virtio direct descriptors and packets 2 KB or larger.
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Analysis
by VulDB Data Team • 03/16/2024
The vulnerability identified as CVE-2019-6676 affects F5 BIG-IP Virtual Edition systems running specific software versions including 15.0.0 through 15.0.1, 14.0.0 through 14.1.2.2, and 13.1.0 through 13.1.3.1. This issue manifests as a potential system instability condition where the Traffic Management Microkernel TMM process may experience unexpected restarts under specific network packet handling conditions. The vulnerability represents a significant concern for network infrastructure reliability and availability, particularly in environments where high-performance virtualized networking is critical.
The technical flaw occurs specifically when the system utilizes virtio direct descriptors in conjunction with network packets that are 2 kilobytes or larger in size. This combination creates a condition where the TMM process encounters a state that triggers an automatic restart mechanism. The root cause appears to be related to how the TMM handles memory management and packet processing when these particular descriptor types are employed with larger packet sizes. This scenario falls under the category of memory corruption or resource management errors that can lead to process termination and system instability.
The operational impact of this vulnerability extends beyond simple service disruption, as it affects the fundamental reliability of BIG-IP virtualized environments. When the TMM process restarts unexpectedly, it can cause temporary network connectivity issues, session disruptions, and potential data loss during transmission. Organizations relying on BIG-IP VE for load balancing, application delivery, or network security functions may experience service degradation or complete outages. The vulnerability particularly affects virtualized deployments where virtio direct descriptors are commonly used for performance optimization, making it a critical concern for cloud-based and virtualized network infrastructures.
Mitigation strategies for CVE-2019-6676 should focus on immediate patching of affected systems to the latest supported software versions that contain the necessary fixes. Organizations should also consider temporarily disabling or modifying the use of virtio direct descriptors for packets larger than 2KB if immediate patching is not feasible. Network administrators should implement monitoring solutions to detect TMM restart patterns and establish incident response procedures to minimize impact during potential occurrences. The vulnerability aligns with CWE-129 Input Validation and CWE-200 Information Exposure categories, while potentially mapping to ATT&CK techniques related to system network configuration and service availability disruption. Organizations should also review their virtualization configurations and ensure proper network segmentation to limit the scope of potential impact from such instability events.