CVE-2025-21906 is a vulnerability identified in the Linux kernel's wireless driver subsystem, specifically within the Intel wireless driver component 'iwlwifi' and its MVM (mac80211-based) implementation. The issue arises in the handling of remain-on-channel (ROC) operations, which are used in Wi-Fi Direct (P2P) scenarios to maintain a channel for peer-to-peer communication. The vulnerability is due to improper state management when the firmware fails to start session protection. In this failure path, the driver calls the cleanup function iwl_mvm_roc_finished() without setting the internal status flag IWL_MVM_STATUS_ROC_P2P_RUNNING. This flag is critical for tracking whether a ROC session is active. If this flag is not set during failure or stop sequences, subsequent operations incorrectly assume that the ROC session is still active, leading to a WARN_ON() kernel warning triggered by an attempt to activate an already active link. This indicates a logic flaw that could cause instability or unexpected behavior in the wireless driver, potentially resulting in kernel warnings or crashes. The vulnerability does not appear to have a direct exploit in the wild and does not have an assigned CVSS score. However, it affects the Linux kernel versions identified by the commit hash 35c1bbd93c4e6969b3ac238b48a8bdff3e223ed8. The root cause is a missing state update in error handling paths, which can lead to inconsistent driver state and potentially impact wireless connectivity reliability and kernel stability.

For European organizations relying on Linux-based systems with Intel wireless hardware, this vulnerability could lead to intermittent wireless connectivity issues or kernel instability, especially in environments utilizing Wi-Fi Direct or peer-to-peer wireless features. While it does not appear to allow direct code execution or privilege escalation, the resulting kernel warnings or crashes could disrupt critical network services, impacting availability. This is particularly relevant for sectors with high dependence on stable wireless communications such as telecommunications, manufacturing automation, healthcare, and public services. Additionally, kernel instability could increase the attack surface by causing system reboots or degraded performance, indirectly affecting operational continuity. Since the flaw is in the wireless driver, devices such as laptops, embedded systems, and IoT devices running vulnerable Linux kernels with Intel wireless chips are at risk. The lack of known exploits suggests the threat is currently low but could be leveraged in targeted attacks or combined with other vulnerabilities to escalate impact.

Organizations should prioritize updating their Linux kernel to versions that include the patch for CVE-2025-21906 once available. Since the vulnerability is related to a specific commit, tracking Linux kernel mailing lists and vendor advisories for patches is essential. For environments where immediate patching is not feasible, disabling Wi-Fi Direct or peer-to-peer wireless features can reduce exposure. Monitoring kernel logs for WARN_ON() messages related to iwlwifi can help detect attempts to trigger the issue. Network administrators should also ensure firmware for Intel wireless devices is updated to the latest versions provided by hardware vendors. In embedded or IoT deployments, firmware updates should be coordinated with device manufacturers. Implementing robust system monitoring and automated reboot policies can mitigate potential availability impacts. Finally, organizations should conduct wireless driver audits and test wireless functionality after updates to confirm stability.