CVE-2021-47017 is a use-after-free vulnerability identified in the Linux kernel's ath10k wireless driver, specifically within the function ath10k_htc_send_bundle. The vulnerability arises because the function frees a network buffer (bundle_skb) using dev_kfree_skb_any(bundle_skb) but subsequently attempts to access the freed buffer's length field (bundle_skb->len). This use-after-free condition can lead to undefined behavior, including potential memory corruption, system crashes, or exploitation by an attacker to execute arbitrary code or escalate privileges. The vulnerability is rooted in improper memory management where the code does not preserve necessary data before freeing the buffer, which was addressed by storing the length in a temporary variable (skb_len) prior to freeing the buffer and then using this stored value instead of accessing the freed memory. The affected versions correspond to specific Linux kernel commits prior to the patch. Although no known exploits are currently reported in the wild, the vulnerability affects the ath10k driver, which supports Qualcomm Atheros 802.11ac wireless devices, commonly used in many Linux-based systems. The flaw could be triggered by sending crafted wireless frames or manipulating the wireless interface, potentially allowing local or remote attackers to cause denial of service or execute arbitrary code depending on the system configuration and exploitability of the use-after-free condition.

For European organizations, this vulnerability poses a risk primarily to systems running Linux kernels with the vulnerable ath10k driver enabled, which includes many enterprise servers, desktops, and embedded devices utilizing Qualcomm Atheros wireless chipsets. Exploitation could lead to denial of service through kernel crashes or, in worst cases, privilege escalation or remote code execution, compromising system confidentiality, integrity, and availability. This is particularly critical for organizations relying on wireless connectivity for critical infrastructure, industrial control systems, or sensitive data processing. The impact is heightened in sectors such as telecommunications, finance, healthcare, and government, where Linux-based systems are prevalent and wireless connectivity is essential. Additionally, the vulnerability could be exploited in environments where attackers have network proximity or local access, making it a concern for corporate networks, public Wi-Fi hotspots, and IoT deployments. Although no active exploits are known, the potential for exploitation exists due to the nature of use-after-free vulnerabilities in kernel code, which are often targeted by advanced threat actors.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2021-47017. Specifically, they should apply the latest stable kernel releases from their distribution vendors that address this vulnerability. For systems where immediate patching is not feasible, disabling or unloading the ath10k driver can mitigate risk, though this may impact wireless functionality. Network segmentation and strict access controls should be enforced to limit exposure of vulnerable systems to untrusted networks. Monitoring for unusual kernel crashes or suspicious wireless activity can help detect exploitation attempts. Additionally, organizations should audit their wireless hardware inventory to identify devices using Qualcomm Atheros chipsets and assess their exposure. Employing host-based intrusion detection systems (HIDS) and maintaining up-to-date security policies for wireless device usage will further reduce risk. Finally, coordinating with Linux distribution maintainers and hardware vendors for timely updates and advisories is recommended to ensure comprehensive protection.