CVE-2023-7192 in Linux
Summary
by MITRE • 01/02/2024
A memory leak problem was found in ctnetlink_create_conntrack in net/netfilter/nf_conntrack_netlink.c in the Linux Kernel. This issue may allow a local attacker with CAP_NET_ADMIN privileges to cause a denial of service (DoS) attack due to a refcount overflow.
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Analysis
by VulDB Data Team • 08/03/2025
The vulnerability identified as CVE-2023-7192 represents a critical memory management flaw within the Linux kernel's netfilter subsystem, specifically affecting the ctnetlink_create_conntrack function in the net/netfilter/nf_conntrack_netlink.c file. This memory leak occurs when processing netfilter connection tracking messages through the netlink interface, creating a scenario where the kernel's reference counting mechanism becomes corrupted due to improper handling of connection tracking objects. The flaw exists at the intersection of network packet filtering and connection state tracking, which are fundamental components of Linux kernel networking infrastructure and form part of the broader NF_CONNTRACK subsystem that maintains state information for network connections.
The technical implementation of this vulnerability stems from a reference count overflow condition that manifests when multiple connection tracking objects are created and destroyed in rapid succession through the netlink interface. When a local attacker possesses CAP_NET_ADMIN capabilities, they can exploit this flaw by repeatedly invoking the ctnetlink_create_conntrack function with malformed or excessive connection tracking requests. The kernel's internal reference counting mechanism fails to properly decrement counters when connection tracking objects are freed, leading to a gradual accumulation of memory that eventually results in system resource exhaustion. This particular issue demonstrates characteristics of CWE-401, which catalogs improper release of memory, and is classified as a denial of service vulnerability due to the system's inability to maintain proper resource allocation. The vulnerability operates at the kernel level and requires elevated privileges to exploit, making it particularly concerning for systems where network administration capabilities are granted to untrusted users or processes.
The operational impact of CVE-2023-7192 extends beyond simple resource exhaustion, as it can severely compromise system stability and availability for legitimate network operations. When the reference count overflow occurs, the kernel's connection tracking subsystem begins to behave unpredictably, potentially causing network connectivity issues, packet loss, or complete network service disruption. The DoS condition can be triggered through a relatively simple attack vector that requires only local access with CAP_NET_ADMIN privileges, making it accessible to users who have been granted network administration rights but may not be fully trusted. This vulnerability affects systems running Linux kernel versions where the NF_CONNTRACK subsystem is active and accessible through netlink interfaces, which includes most modern server and desktop distributions. The impact is particularly severe in environments where continuous network connectivity is critical, such as enterprise data centers, network infrastructure devices, or systems running network services that depend heavily on connection tracking.
Mitigation strategies for CVE-2023-7192 must address both immediate operational concerns and long-term system security. The primary recommendation involves applying the latest kernel security patches that contain the fix for the reference count overflow issue in the ctnetlink_create_conntrack function. System administrators should also implement strict privilege controls to minimize the number of users or processes with CAP_NET_ADMIN capabilities, as this reduces the attack surface for exploitation. Network monitoring should be enhanced to detect unusual patterns in connection tracking operations that might indicate exploitation attempts, and system resource limits should be configured to prevent complete resource exhaustion even if the vulnerability is exploited. The ATT&CK framework categorizes this vulnerability under privilege escalation and resource exhaustion tactics, with the specific technique being the exploitation of kernel memory management flaws. Organizations should also consider implementing automated patch management processes to ensure timely deployment of security updates, as this vulnerability can be leveraged by attackers to disrupt critical network services and potentially gain further system access through cascading failures.