CVE-2024-26808 in Linux
Summary
by MITRE • 04/04/2024
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nft_chain_filter: handle NETDEV_UNREGISTER for inet/ingress basechain
Remove netdevice from inet/ingress basechain in case NETDEV_UNREGISTER event is reported, otherwise a stale reference to netdevice remains in the hook list.
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Analysis
by VulDB Data Team • 08/04/2025
This vulnerability exists within the Linux kernel's netfilter subsystem, specifically affecting the nft_chain_filter implementation that manages network filtering chains. The issue occurs when handling network device lifecycle events, particularly during the unregistering process of network devices. When a network device is unregistered from the system, the kernel fails to properly remove the associated netdevice reference from the inet/ingress basechain hook list, creating a stale reference that persists in memory. This represents a classic resource management flaw where cleanup operations are incomplete or omitted during device removal scenarios.
The technical flaw stems from inadequate handling of the NETDEV_UNREGISTER event within the netfilter framework's chain filtering mechanism. During normal operation, network devices register themselves with various hook points in the network stack, including inet/ingress basechains that are responsible for filtering incoming packets at the network layer. When a device is unregistered, the system should automatically clean up all references to that device within the filtering infrastructure. However, the current implementation fails to properly process the NETDEV_UNREGISTER event for inet/ingress basechains, leaving dangling pointers that can cause system instability or unexpected behavior.
The operational impact of this vulnerability extends beyond simple memory leaks, as it can lead to system crashes or unpredictable network filtering behavior. When stale netdevice references remain in the hook list, they can cause null pointer dereferences or access violations when the system attempts to process packets through these corrupted chains. This issue is particularly concerning in environments where network devices are frequently added and removed, such as containerized environments, virtualized networks, or systems with dynamic network configuration. The vulnerability affects the integrity of the netfilter subsystem and can compromise network security policies that depend on proper chain management.
The mitigation strategy involves implementing proper cleanup procedures during network device unregister events, ensuring that all references to the netdevice are removed from the inet/ingress basechain hook list. This aligns with common security practices for resource management and follows the principle of least privilege by ensuring that only valid network references remain in the filtering infrastructure. The fix requires modifying the nft_chain_filter implementation to properly handle the NETDEV_UNREGISTER event and remove corresponding entries from all relevant hook lists. This vulnerability demonstrates the importance of proper event handling in kernel subsystems and the need for comprehensive testing of device lifecycle management scenarios, particularly in complex networking environments where multiple subsystems interact with shared resources. The issue can be addressed through kernel updates that implement the necessary reference cleanup logic, following established security practices for kernel vulnerability remediation and system stability maintenance.
This vulnerability classification aligns with CWE-459, which describes incomplete cleanup issues in software systems, and relates to ATT&CK technique T1059.007 for privilege escalation through kernel exploits. The problem demonstrates how seemingly minor resource management oversights can create significant security implications in operating system kernels.