CVE-2025-21843 is a vulnerability identified in the Linux kernel, specifically within the Direct Rendering Manager (DRM) subsystem's panthor driver component. The issue arises in the panthor_ioctl_dev_query() function, where a data structure named 'priorities_info' is used without proper initialization. This uninitialized variable can contain garbage values, which are then copied to a user-space object via the PANTHOR_UOBJ_SET() macro or function. The root cause is the failure to initialize 'priorities_info' before its use, leading to potential leakage of kernel memory contents or undefined behavior. The vulnerability was addressed by introducing a memset operation to zero-initialize 'priorities_info', ensuring no residual or garbage data is exposed to user space. Since this flaw involves leaking uninitialized kernel memory to user space, it can be classified as an information disclosure vulnerability. There is no indication that this vulnerability allows privilege escalation or arbitrary code execution. The affected product is the Linux kernel, with the specific affected versions identified by the commit hash 'f70000ef23527f6d928d1175c66c5fafa968814b'. No CVSS score has been assigned yet, and no known exploits are reported in the wild as of the publication date (March 7, 2025).

For European organizations, the impact of CVE-2025-21843 primarily concerns confidentiality risks due to potential leakage of sensitive kernel memory contents to unprivileged user-space processes. While the vulnerability does not appear to allow direct privilege escalation or code execution, information disclosure can aid attackers in crafting more effective attacks, such as bypassing security mechanisms or escalating privileges through subsequent vulnerabilities. Organizations relying heavily on Linux-based systems, especially those using DRM panthor drivers (commonly found in graphics subsystems), may be at risk if untrusted users or processes can invoke the vulnerable ioctl. This is particularly relevant for multi-tenant environments, cloud providers, and organizations running containerized workloads on Linux where isolation boundaries depend on kernel integrity. The vulnerability could also affect embedded Linux systems used in industrial control or critical infrastructure within Europe, potentially exposing sensitive operational data. However, since exploitation requires interaction with the specific ioctl interface, the attack surface is somewhat limited to environments where untrusted users have access to the affected device nodes.

To mitigate CVE-2025-21843, European organizations should promptly apply the official Linux kernel patches that initialize the 'priorities_info' structure properly. Kernel updates containing the fix should be prioritized in patch management cycles. For environments where immediate patching is not feasible, administrators should restrict access to the vulnerable panthor device nodes by tightening file permissions and using Linux security modules (e.g., SELinux or AppArmor) to limit ioctl calls to trusted processes only. Additionally, monitoring and auditing usage of the panthor ioctl interfaces can help detect anomalous or unauthorized access attempts. Organizations should also review their deployment of DRM drivers and consider disabling or unloading the panthor driver if it is not required, thereby reducing the attack surface. Finally, maintaining robust kernel hardening and employing runtime security tools that detect unusual kernel memory disclosures can provide additional defense layers.