CVE-2025-71227: Linux Kernel WiFi Channel Vulnerability

CVE-2025-71227 Overview

CVE-2025-71227 is a medium-severity vulnerability in the Linux kernel's mac80211 wireless subsystem. The issue stems from a WARN condition triggered when a connection is attempted on an invalid Wi-Fi channel. A regulatory update can disable a channel between scan completion and the subsequent connection attempt, causing the kernel to emit an unnecessary warning. On systems configured with panic_on_warn, this warning escalates to a kernel panic and produces a local denial-of-service condition. The flaw was identified through syzbot fuzzing of the wireless stack. The fix replaces the WARN with a more informative error message.

Critical Impact
A local user can trigger a kernel warning during Wi-Fi connection on an invalidated channel, leading to denial of service on systems with panic_on_warn enabled.

Affected Products

Linux Kernel 6.19-rc1
Linux Kernel 6.19-rc2
Linux Kernel 6.19-rc3

Discovery Timeline

2026-02-18 - CVE-2025-71227 published to NVD
2026-03-18 - Last updated in NVD database

Technical Details for CVE-2025-71227

Vulnerability Analysis

The vulnerability resides in the Linux kernel's mac80211 subsystem, which implements the software MAC layer for IEEE 802.11 wireless devices. During the connection workflow, cfg80211_get_ies_channel_number validates that a target channel is usable before the connection sequence begins. However, the regulatory database may change between this validation and the actual association attempt, disabling the previously valid channel.

When the connection logic later observes the now-invalid channel state, it hits a WARN macro. On hardened kernels configured with panic_on_warn, this transitions a recoverable condition into a full kernel panic. The result is a local availability impact without affecting confidentiality or integrity.

The vulnerability is classified under [NVD-CWE-noinfo] due to insufficient categorization data. Exploitation requires local low-privilege access and no user interaction.

Root Cause

The root cause is an overly strict invariant assumption in the mac80211 connection path. The code assumed that a channel validated during scanning would remain valid through the connection phase. Regulatory changes between these two phases violate this assumption. The original WARN treats a legitimate runtime race condition as a programming error.

Attack Vector

A local user with the ability to trigger wireless connection operations and influence regulatory state can race the channel validation against the connection attempt. The syzbot fuzzer reached this condition through automated kernel exploration. The EPSS score for this CVE is 0.019% with a percentile of 5.36, indicating low expected exploitation activity.

No public proof-of-concept or in-the-wild exploitation has been reported. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2025-71227

Indicators of Compromise

Kernel log entries containing WARN traces originating from mac80211 channel handling functions during Wi-Fi association.
Unexpected kernel panics on systems with panic_on_warn=1 correlated with wireless connection attempts.
Repeated wireless connection failures coinciding with regulatory domain changes via iw reg set or crda events.

Detection Strategies

Monitor dmesg and journalctl -k output for warning traces referencing mac80211 and channel validation functions.
Correlate wireless subsystem warnings with regulatory domain change events through audit logging.
Track kernel version inventory to identify hosts running Linux 6.19-rc1 through 6.19-rc3.

Monitoring Recommendations

Forward kernel ring buffer events to a centralized logging platform for analysis of mac80211 warnings.
Alert on kernel panic events and capture vmcore dumps for post-incident triage.
Inventory and monitor systems running affected Linux 6.19 release candidate kernels in production or test environments.

How to Mitigate CVE-2025-71227

Immediate Actions Required

Identify all systems running Linux kernel 6.19-rc1, 6.19-rc2, or 6.19-rc3 and prioritize them for patching.
Apply the upstream fix commits 10d3ff7e5812c8d70300f6fa8f524009a06aa7e1 and 99067b58a408a384d2a45c105eb3dce980a862ce from the stable kernel tree.
Disable panic_on_warn on non-production systems to prevent denial-of-service escalation while patches are validated.

Patch Information

The Linux kernel maintainers resolved the issue by replacing the WARN macro with a descriptive error message. The fix is published in the stable tree under the Linux Kernel Commit Update and Linux Kernel Commit Change. Administrators should rebuild kernels from a patched source tree or upgrade to a vendor kernel that incorporates these commits.

Workarounds

Avoid enabling panic_on_warn on systems running affected release candidate kernels until the patch is deployed.
Restrict local user privileges to limit who can initiate wireless connection operations or modify regulatory state.
Pin production workloads to stable Linux kernel releases rather than 6.19 release candidates.

bash

# Verify current kernel version and panic_on_warn setting
uname -r
sysctl kernel.panic_on_warn

# Temporarily disable panic_on_warn until patch is applied
sysctl -w kernel.panic_on_warn=0