CVE-2022-1016 in Linux
Summary
by MITRE • 08/29/2022
A flaw was found in the Linux kernel in net/netfilter/nf_tables_core.c:nft_do_chain, which can cause a use-after-free. This issue needs to handle 'return' with proper preconditions, as it can lead to a kernel information leak problem caused by a local, unprivileged attacker.
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Analysis
by VulDB Data Team • 05/18/2025
The vulnerability identified as CVE-2022-1016 represents a critical use-after-free condition within the Linux kernel's netfilter subsystem, specifically in the nftables core implementation. This flaw exists in the net/netfilter/nf_tables_core.c file at the nft_do_chain function, where improper handling of 'return' operations creates a scenario where freed memory can be accessed by subsequent operations. The vulnerability stems from inadequate precondition validation during the execution flow of netfilter tables chains, allowing malicious code to manipulate the kernel's memory management system. The flaw is particularly concerning because it can be exploited by local unprivileged users who have minimal system access rights, making it a significant threat vector for privilege escalation and system compromise. The issue manifests as a kernel information leak that occurs when the system attempts to access memory that has already been freed, potentially exposing sensitive kernel data structures and memory contents to unauthorized access.
The technical exploitation of this vulnerability requires understanding the kernel's netfilter framework and how nftables processes chain execution. When nft_do_chain encounters specific return conditions without proper memory management checks, it can lead to a state where memory allocated to netfilter chain structures becomes available for reuse while still being referenced by ongoing operations. This creates a race condition scenario where subsequent kernel operations may access the freed memory location, resulting in unpredictable behavior including kernel crashes, memory corruption, or information disclosure. The use-after-free condition specifically relates to CWE-416 which defines the improper release of memory resources, and the vulnerability can be mapped to ATT&CK technique T1068 which covers the exploitation of local privilege escalation vulnerabilities. The flaw's impact extends beyond simple information leakage as it can be leveraged to execute arbitrary code within kernel space, potentially leading to complete system compromise.
From an operational standpoint, this vulnerability presents a significant risk to systems running Linux kernels with netfilter and nftables support, particularly those with local user access or containerized environments where unprivileged users might be present. The local nature of the exploit means that any user with basic system access can potentially trigger the vulnerability, making it a critical concern for multi-user systems, cloud environments, and server deployments. Organizations using Linux systems with active netfilter configurations should prioritize patching this vulnerability as it can be exploited without requiring elevated privileges, and the information leak aspect could expose kernel memory layouts, security keys, or other sensitive data. The attack surface is broad since nftables is commonly used for firewall and network filtering operations across various Linux distributions, making this vulnerability widespread in scope and impact.
Mitigation strategies for CVE-2022-1016 should include immediate kernel updates from vendors such as Red Hat, Ubuntu, Debian, and other distribution maintainers who have released patches addressing the use-after-free condition. System administrators should ensure that all Linux systems running affected kernel versions receive security updates promptly, as the vulnerability can be exploited remotely if network services are accessible to unprivileged users. Additional defensive measures include implementing strict access controls to limit local user privileges where possible, monitoring for unusual kernel memory access patterns, and employing kernel hardening techniques such as stack canaries, kernel address space layout randomization, and control flow integrity checks. Network segmentation and privilege separation can help reduce the attack surface, while regular security audits should verify that netfilter configurations are not unnecessarily complex, as simpler configurations may reduce the likelihood of triggering the specific race condition that leads to the vulnerability exploitation. The patching process should be carefully monitored to ensure that kernel updates do not introduce compatibility issues with existing network filtering rules or applications relying on nftables functionality.