CVE-2023-4133 in Linux
Summary
by MITRE • 08/03/2023
A use-after-free vulnerability was found in the cxgb4 driver in the Linux kernel. The bug occurs when the cxgb4 device is detaching due to a possible rearming of the flower_stats_timer from the work queue. This flaw allows a local user to crash the system, causing a denial of service condition.
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Analysis
by VulDB Data Team • 07/24/2025
The CVE-2023-4133 vulnerability represents a critical use-after-free condition within the cxgb4 network driver component of the Linux kernel ecosystem. This flaw resides in the handling of device detachment processes where the flower_stats_timer mechanism can be inadvertently rearmed from a work queue context, creating a dangerous race condition scenario. The cxgb4 driver is responsible for managing chelsio communications adapters, which are commonly used in high-performance networking environments for data center and enterprise applications. The vulnerability specifically manifests during the device teardown phase when the kernel attempts to clean up resources associated with the network interface, making it particularly concerning for systems where network reliability is paramount.
The technical implementation of this vulnerability stems from improper memory management during the driver's device removal sequence. When the cxgb4 driver undergoes detachment, it schedules work items to handle cleanup operations including timer rearming. The use-after-free condition occurs because the kernel fails to properly synchronize access to memory regions that may be freed while another execution path attempts to reference them. This particular flaw demonstrates poor resource lifecycle management where the flower_stats_timer structure remains accessible even after the device has been marked for removal, allowing subsequent operations to reference deallocated memory. The vulnerability is classified under CWE-416 as a use-after-free error, which represents a well-known category of memory safety issues that frequently leads to system instability and potential privilege escalation vectors.
The operational impact of CVE-2023-4133 extends beyond simple denial of service conditions, as local users with access to the system can exploit this weakness to cause complete system crashes. This vulnerability particularly affects Linux systems running kernel versions that include the cxgb4 driver, commonly found in enterprise server environments, cloud infrastructure deployments, and high-performance computing clusters. The exploitation process requires local system access but does not necessitate elevated privileges, making it a significant concern for multi-tenant environments where privilege separation is critical. The vulnerability can be triggered through normal network device operations, making it difficult to detect and prevent in production environments. Security researchers have noted that this flaw can be leveraged to create persistent denial of service conditions that may require manual system intervention to resolve, potentially leading to extended downtime in mission-critical systems.
Mitigation strategies for CVE-2023-4133 should prioritize immediate kernel updates from vendor sources to address the underlying memory management issues. System administrators should implement comprehensive monitoring solutions to detect potential exploitation attempts through anomalous device detachment patterns or system crash reports. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service, where attackers leverage system instability to disrupt network services. Organizations should also consider implementing additional network segmentation and access controls to limit local user privileges where possible. Security teams should monitor for exploitation attempts through system logs, particularly focusing on kernel oops messages and device driver error reports. The recommended patching strategy involves applying the latest kernel security updates from the Linux kernel maintainers, as the vulnerability has been addressed through proper synchronization mechanisms and memory deallocation procedures. Network administrators should also consider implementing automated patch management solutions to ensure timely deployment of security fixes across enterprise environments.