CVE-2023-0266 is a use-after-free vulnerability identified in the ALSA (Advanced Linux Sound Architecture) PCM (Pulse Code Modulation) package within the Linux Kernel, specifically affecting version 4.14. The vulnerability stems from missing locking mechanisms in the SNDRV_CTL_IOCTL_ELEM_READ32 and SNDRV_CTL_IOCTL_ELEM_WRITE32 ioctl handlers. These missing locks allow a race condition that can lead to a use-after-free scenario, where kernel memory is accessed after it has been freed. This flaw can be exploited by a local attacker with low privileges (system user) to escalate their privileges to ring0, effectively gaining full kernel-level control over the system. The vulnerability does not require user interaction but does require local access, which could be obtained via compromised user accounts or local access vectors. The impact includes potential confidentiality loss (limited), high integrity compromise (full kernel control), and high availability impact (system stability or denial of service). Although no known exploits have been reported in the wild, the vulnerability's characteristics and severity score of 7.9 (CVSS v3.1) classify it as high risk. The recommended mitigation is to upgrade the Linux kernel to versions including or beyond the commit 56b88b50565cd8b946a2d00b0c83927b7ebb055e, which addresses the locking issue. This vulnerability is particularly critical for environments where Linux kernel 4.14 is in use, including embedded systems, servers, and enterprise Linux distributions that have not applied the patch.

For European organizations, the impact of CVE-2023-0266 is significant due to the potential for local privilege escalation to kernel-level access. This can lead to full system compromise, allowing attackers to bypass security controls, access sensitive data, install persistent malware, or disrupt critical services. Organizations relying on Linux kernel 4.14, especially in sectors such as finance, telecommunications, energy, and government, face heightened risks. The vulnerability could be leveraged in multi-user environments or where attackers have gained limited local access, such as through compromised user credentials or insider threats. The ability to escalate privileges to ring0 can facilitate lateral movement and deeper network infiltration. Additionally, the lack of known exploits in the wild does not diminish the urgency, as public disclosure may prompt attackers to develop exploits. The impact on availability is also notable, as exploitation could cause system crashes or denial of service. Overall, the vulnerability threatens confidentiality (limited), integrity (high), and availability (high) of affected systems.

European organizations should immediately assess their Linux kernel versions and identify systems running version 4.14 or other affected versions. The primary mitigation is to upgrade the Linux kernel to a version that includes the fix beyond commit 56b88b50565cd8b946a2d00b0c83927b7ebb055e. For distributions that backport patches, ensure that the latest security updates are applied. In environments where immediate kernel upgrades are not feasible, consider implementing strict access controls to limit local user privileges and isolate critical systems. Employ kernel hardening techniques such as SELinux or AppArmor to restrict unauthorized kernel interactions. Monitor system logs for unusual ioctl calls or suspicious local activity that could indicate exploitation attempts. Conduct regular vulnerability scanning and penetration testing focusing on local privilege escalation vectors. Finally, maintain an incident response plan to quickly address any detected exploitation attempts.