CVE-2024-49939 is a vulnerability in the Linux kernel specifically affecting the rtw89 Wi-Fi driver, which is responsible for Realtek 8922ae wireless chipsets. The issue arises during the WoWLAN (Wake on Wireless LAN) resume flow when a SER (Sudden Error Recovery) Level 2 event occurs. The vulnerability is triggered because the function ieee80211_reconfig() initiates an add interface operation. However, due to a failure return from rtw89_wow_resume(), the add interface operation is executed twice, causing the same interface to be added twice to a linked list. This double addition corrupts the kernel's linked list data structure, leading to a kernel panic and system crash. The kernel panic is evidenced by the BUG report at lib/list_debug.c:37, indicating an invalid opcode triggered by the double list addition. The stack trace shows the failure occurs in __list_add_valid_or_report(), called from rtw89_ops_add_interface() and ieee80211_reconfig(), confirming the root cause is the double addition of the interface in the rtw89 driver during WoWLAN resume. This vulnerability can cause denial of service (DoS) by crashing the kernel, requiring a system reboot. Since it occurs in the kernel space and affects wireless network interface management, it impacts system stability and availability. The vulnerability does not appear to require user interaction or elevated privileges beyond those needed to trigger the WoWLAN resume flow. The affected Linux kernel versions include those containing the specified commit e3ec7017f6a20d12ddd9fe23d345ebb7b8c104dd, which corresponds to recent kernel releases around version 6.6.30. No known exploits are reported in the wild yet, and no CVSS score has been assigned. The patch involves adding a check to prevent the double addition of the interface to the list, thus avoiding the kernel panic.

For European organizations, this vulnerability poses a risk primarily to systems running Linux kernels with the rtw89 driver enabled and using Realtek 8922ae wireless chipsets. Such systems could experience unexpected kernel panics and crashes during WoWLAN resume operations, leading to denial of service. This can disrupt critical services, especially in environments relying on wireless connectivity for remote management, IoT devices, or embedded systems. The impact is more severe in sectors with high availability requirements such as telecommunications, healthcare, manufacturing, and public infrastructure. Additionally, repeated kernel panics could lead to data loss or corruption if systems are rebooted abruptly. Although no remote code execution or privilege escalation is indicated, the availability impact alone can cause operational disruptions. European organizations using Linux-based wireless infrastructure, laptops, or embedded devices with affected drivers should consider this vulnerability a stability and availability risk. Since the vulnerability is triggered during WoWLAN resume, devices that frequently use WoWLAN features are at higher risk. The lack of known exploits reduces immediate threat but does not eliminate risk, especially as attackers may develop exploits targeting this vulnerability to cause denial of service in critical systems.

1. Apply the latest Linux kernel updates that include the patch for CVE-2024-49939 as soon as they become available. Monitor kernel mailing lists and vendor advisories for patch releases. 2. For systems where immediate patching is not feasible, consider disabling WoWLAN functionality to prevent triggering the vulnerable code path. This can be done via network manager settings or kernel module parameters. 3. Audit and inventory devices using the Realtek 8922ae chipset and the rtw89 driver to identify potentially vulnerable endpoints. 4. Implement monitoring for kernel panics and unexpected reboots on Linux systems to detect potential exploitation or triggering of this vulnerability. 5. For critical infrastructure, consider deploying redundant systems or failover mechanisms to maintain availability in case of kernel crashes. 6. Engage with Linux distribution vendors and hardware manufacturers to confirm patch availability and coordinate timely updates. 7. Limit physical and network access to devices with this vulnerability to reduce the risk of triggering the WoWLAN resume flow maliciously or accidentally. 8. Review and test kernel updates in controlled environments before wide deployment to ensure stability and compatibility.