CVE-2025-71227 Overview
A vulnerability has been identified in the Linux kernel's WiFi mac80211 subsystem related to improper handling of connections on invalid channels. The issue stems from a race condition where regulatory changes can disable a channel between the scanning phase (when the channel is validated by cfg80211_get_ies_channel_number) and the subsequent connection attempt. This timing gap can result in connection attempts on channels that are no longer valid, triggering kernel warnings.
Critical Impact
This vulnerability affects Linux kernel WiFi functionality and could potentially be leveraged to cause system instability through triggered kernel warnings or denial of service conditions on systems with active wireless connections.
Affected Products
- Linux kernel with mac80211 WiFi subsystem
- Systems using cfg80211 wireless configuration
- Linux-based devices with active WiFi connections subject to regulatory changes
Discovery Timeline
- 2026-02-18 - CVE CVE-2025-71227 published to NVD
- 2026-02-18 - Last updated in NVD database
Technical Details for CVE-2025-71227
Vulnerability Analysis
The vulnerability exists within the mac80211 subsystem of the Linux kernel, which is responsible for handling WiFi operations. The core issue involves a race condition between channel validation during scanning and subsequent connection attempts. When the wireless regulatory domain changes (for example, when a device moves between regions with different wireless regulations), channels that were previously valid during the scanning phase may become disabled before a connection is fully established.
The original implementation would trigger a kernel WARN when encountering this scenario, which provides limited debugging information and could potentially be abused to cause system instability. The fix replaces the warning with a more informative error message, improving debuggability while preventing potential exploitation.
Root Cause
The root cause is a Time-of-Check Time-of-Use (TOCTOU) race condition in the WiFi connection handling code. The channel validity is checked by cfg80211_get_ies_channel_number during the scanning phase, but this validation can become stale if regulatory changes occur before the connection is completed. The mac80211 subsystem did not properly handle this edge case, leading to unexpected warnings when attempting connections on subsequently invalidated channels.
Attack Vector
The attack vector for this vulnerability involves manipulating or triggering regulatory domain changes on a target system. An attacker with the ability to influence regulatory notifications or force regulatory domain updates could potentially:
- Wait for a system to scan and identify valid channels
- Trigger a regulatory change that invalidates the target channel
- Cause the system to attempt a connection on the now-invalid channel
- Trigger kernel warnings that could impact system stability
The vulnerability was discovered through fuzzing by syzbot, indicating that the race condition window, while small, is reproducible under specific conditions.
Detection Methods for CVE-2025-71227
Indicators of Compromise
- Kernel log entries containing mac80211 warnings related to invalid channel connections
- Unexpected WiFi disconnections coinciding with regulatory domain changes
- System logs showing repeated attempts to connect on disabled channels
- Kernel warning traces originating from the mac80211 subsystem
Detection Strategies
- Monitor kernel logs for mac80211-related warnings and errors during WiFi operations
- Implement monitoring for regulatory domain changes and correlate with connection failures
- Deploy kernel instrumentation to track race conditions in the wireless subsystem
- Use SentinelOne Singularity to detect anomalous kernel behavior patterns
Monitoring Recommendations
- Enable verbose logging for the mac80211 and cfg80211 kernel modules
- Configure alerting on kernel WARN messages from wireless subsystems
- Monitor for patterns of repeated WiFi connection failures that may indicate exploitation attempts
- Track regulatory domain change events and correlate with system stability issues
How to Mitigate CVE-2025-71227
Immediate Actions Required
- Apply the latest Linux kernel patches that address this vulnerability
- Review systems with active wireless connections for signs of exploitation
- Consider temporarily disabling automatic regulatory domain updates on critical systems
- Monitor kernel logs for mac80211 warnings indicating potential exploitation attempts
Patch Information
The Linux kernel maintainers have released patches to address this vulnerability. The fix replaces the kernel WARN with an informative error message, properly handling the edge case where regulatory changes invalidate channels between scanning and connection. The patches are available through the official kernel.org stable branches:
Workarounds
- Disable automatic regulatory domain updates if immediate patching is not possible
- Implement network monitoring to detect anomalous WiFi behavior patterns
- Consider using wired connections on critical systems until patches can be applied
- Restrict local access to prevent manipulation of wireless regulatory settings
# Check current kernel version and wireless modules
uname -r
lsmod | grep -E "mac80211|cfg80211"
# Monitor kernel logs for mac80211 warnings
dmesg | grep -i mac80211
# Check regulatory domain status
iw reg get
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
