CVE-2024-53156 is a vulnerability identified in the Linux kernel's wireless driver for Atheros 9k (ath9k), specifically within the htc_connect_service() function. The issue arises due to insufficient validation of the conn_rsp_epid parameter, which is used as an index into an array of htc_endpoint structures. The vulnerability was discovered through fuzz testing, which revealed an out-of-bounds array access when conn_rsp_epid is set to 255, exceeding the valid range for the array (which has 22 elements). This unchecked array index can lead to undefined behavior including potential memory corruption, kernel crashes, or privilege escalation. The vulnerability is located in the wireless driver code (drivers/net/wireless/ath/ath9k/htc_hst.c), which handles communication with the wireless hardware. The root cause is the lack of a range check on conn_rsp_epid before it is used to index the htc_endpoint array. The fix involves adding a proper range check to ensure conn_rsp_epid is within valid bounds before use, preventing out-of-bounds access. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The affected Linux kernel versions are identified by a specific commit hash (fb9987d0f748c983bb795a86f47522313f701a08), indicating this is a recent or development branch vulnerability. This vulnerability affects systems running Linux kernels with the vulnerable ath9k driver, which is common in many Linux distributions supporting Atheros wireless chipsets. Because it is a kernel-level vulnerability, exploitation could lead to serious impacts such as denial of service or privilege escalation if an attacker can trigger the bug, especially on systems using affected wireless hardware.

For European organizations, this vulnerability poses a risk primarily to systems running Linux with Atheros 9k wireless chipsets, which are widely used in laptops, embedded devices, and some networking equipment. Exploitation could allow attackers to cause kernel crashes leading to denial of service or potentially execute arbitrary code with kernel privileges if combined with other vulnerabilities or attack vectors. This could impact critical infrastructure, enterprise networks, and government systems relying on Linux-based devices for wireless connectivity. The vulnerability could be leveraged in targeted attacks against organizations with high reliance on Linux wireless networking, such as telecommunications providers, research institutions, and public sector entities. The lack of authentication or user interaction requirements for triggering the vulnerability (assuming local or remote triggering via wireless communication) increases the risk. However, the exploitability depends on the attacker’s ability to interact with the vulnerable wireless driver, which may require proximity or network access. The vulnerability could disrupt operations, compromise system integrity, and potentially expose sensitive data if exploited in combination with other flaws. Given the widespread use of Linux in European IT environments, especially in government and technology sectors, the impact could be significant if not mitigated promptly.

1. Apply Kernel Updates: European organizations should prioritize applying the patch or updated Linux kernel versions that include the range check fix for conn_rsp_epid in the ath9k driver as soon as they become available from their Linux distribution vendors. 2. Wireless Hardware Inventory: Conduct an inventory of devices using Atheros 9k wireless chipsets and assess exposure. 3. Network Segmentation: Limit access to critical Linux systems with vulnerable wireless drivers by segmenting networks and restricting wireless access where possible. 4. Disable Unused Wireless Interfaces: On systems where wireless connectivity is not required, disable the wireless interface or unload the ath9k driver to reduce attack surface. 5. Monitor for Anomalies: Implement monitoring for unusual kernel crashes or wireless driver errors that could indicate exploitation attempts. 6. Use Security Modules: Employ Linux security modules (e.g., SELinux, AppArmor) to limit the impact of potential kernel exploits. 7. Vendor Coordination: Engage with Linux distribution vendors and hardware manufacturers for timely updates and advisories. 8. Restrict Physical Access: Since exploitation may require proximity, enforce physical security controls to limit unauthorized access to wireless networks and devices.