CVE-2025-21979 is a use-after-free vulnerability in the Linux kernel's wireless configuration subsystem, specifically within the cfg80211 component that manages wireless device configuration. The vulnerability arises from improper handling of asynchronous work items (wiphy_work) associated with wireless physical devices (wiphy). When a wiphy device is allocated and initialized, a wiphy_work can be queued to run asynchronously. However, if the wiphy is freed (via wiphy_free) before the queued work executes, the work will eventually run referencing freed memory, leading to a use-after-free condition. This can cause undefined behavior such as kernel crashes, memory corruption, or potentially arbitrary code execution in kernel context. The root cause is the failure to cancel the pending wiphy_work before freeing the wiphy structure. The fix involves ensuring that any queued wiphy_work is canceled before the wiphy memory is released, preventing the work from running on invalid memory. This vulnerability affects multiple versions of the Linux kernel as indicated by the affected commit hashes, and it was publicly disclosed on April 1, 2025. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability poses a significant risk to any systems running vulnerable Linux kernel versions with wireless networking enabled. Since cfg80211 is a core wireless configuration interface, many servers, desktops, and embedded devices using Linux with Wi-Fi capabilities could be affected. Exploitation could lead to kernel crashes causing denial of service, or in worst cases, privilege escalation or arbitrary code execution at the kernel level, compromising system integrity and confidentiality. This is particularly critical for infrastructure providers, telecommunications, and enterprises relying on Linux-based wireless networking. The vulnerability could disrupt business operations, lead to data breaches, or facilitate lateral movement within networks if exploited. Although no active exploits are known, the ease of triggering asynchronous work items and the kernel-level impact make this a high-risk issue that requires prompt attention.

Organizations should promptly apply the official Linux kernel patches that cancel wiphy_work before freeing the wiphy structure. If immediate patching is not feasible, temporary mitigations include disabling wireless interfaces or removing wireless drivers to reduce attack surface. System administrators should audit their Linux kernel versions against the affected commits and upgrade to patched versions as soon as they become available. Additionally, monitoring kernel logs for unusual crashes or memory errors related to wireless components can help detect exploitation attempts. Employing kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and enabling security modules like SELinux or AppArmor may also reduce exploitation risk. Finally, organizations should maintain robust incident response plans to quickly address any signs of compromise stemming from this vulnerability.