CVE-2023-53802 in Linux
Summary
by MITRE • 12/09/2025
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath9k: htc_hst: free skb in ath9k_htc_rx_msg() if there is no callback function
It is stated that ath9k_htc_rx_msg() either frees the provided skb or passes its management to another callback function. However, the skb is not freed in case there is no another callback function, and Syzkaller was able to cause a memory leak. Also minor comment fix.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
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Analysis
by VulDB Data Team • 03/29/2026
The vulnerability CVE-2023-53802 represents a memory leak condition within the Linux kernel's ath9k wireless driver implementation, specifically in the ath9k_htc_rx_msg() function. This issue affects the ath9k wireless networking subsystem that handles USB-based wireless adapters, particularly those using the ath9k_htc firmware interface. The flaw manifests when processing received wireless frames through the HTC (Host Target Communication) layer, where proper memory management fails to occur under certain conditions. The vulnerability was identified through automated kernel testing conducted by the Linux Verification Center using the Syzkaller fuzzer, which is a powerful tool designed to discover kernel-level memory corruption and resource management issues.
The technical root cause of this vulnerability lies in the improper handling of socket buffer (skb) memory management within the ath9k_htc_rx_msg() function. According to the kernel's design pattern, this function should either free the provided skb or transfer its ownership to another callback function for processing. However, when no callback function exists to handle the skb, the function fails to free the memory, resulting in a memory leak. This condition occurs because the code path does not properly account for the scenario where the skb needs to be explicitly freed when no further processing is required. The issue demonstrates a classic violation of proper resource management principles where allocated memory is not properly deallocated, leading to gradual memory consumption over time. This type of vulnerability falls under CWE-401: Improper Release of Memory Before Removing Last Reference, which is a fundamental memory management error that can lead to various security implications including denial of service.
The operational impact of this vulnerability extends beyond simple memory consumption, as it represents a potential vector for denial of service attacks against systems running affected wireless networking drivers. While the immediate security risk may appear limited to memory exhaustion, such leaks can accumulate over time and potentially lead to system instability or performance degradation. The vulnerability affects systems using ath9k wireless drivers with USB-based hardware, which includes a wide range of wireless network adapters that utilize the ath9k_htc firmware interface. The memory leak could be exploited by an attacker to gradually consume system resources, potentially causing the system to become unresponsive or crash under sustained load conditions. This issue is particularly concerning in environments where wireless connectivity is critical and continuous operation is required, as the memory leak could eventually lead to system-wide resource exhaustion.
The mitigation strategy for this vulnerability involves applying the official kernel patch that corrects the memory management logic in the ath9k_htc_rx_msg() function to ensure that skbs are properly freed when no callback function exists. System administrators should prioritize updating their kernel versions to include this fix, particularly in production environments where wireless networking is actively used. Additionally, monitoring for unusual memory consumption patterns in wireless networking subsystems can help detect potential exploitation attempts. The fix aligns with best practices for kernel memory management and follows the ATT&CK framework's approach to addressing memory corruption vulnerabilities through proper resource handling. Organizations should also consider implementing network monitoring solutions that can detect anomalous wireless traffic patterns that might indicate exploitation attempts, while maintaining regular kernel update schedules to address similar vulnerabilities proactively. The vulnerability serves as a reminder of the importance of thorough memory management in kernel space code and demonstrates how seemingly minor implementation flaws can lead to significant operational impacts in wireless networking systems.