CVE-2025-71224: Linux Kernel mac80211 OCB Vulnerability

CVE-2025-71224 Overview

A race condition vulnerability has been identified in the Linux kernel's WiFi mac80211 subsystem, specifically affecting the Outside the Context of a BSS (OCB) interface handling. The vulnerability exists in the ieee80211_ocb_rx_no_sta() function, which incorrectly assumes a valid channel context is always present. This assumption fails when RX (receive) operations occur before the JOIN_OCB command is executed, leading to potential kernel warnings and system instability.

The OCB mode is used for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications in Dedicated Short-Range Communications (DSRC) systems. When an OCB interface receives packets before it has properly joined a channel, the kernel attempts to access an invalid channel context, triggering warnings in the RX path.

Critical Impact

Systems using OCB mode for vehicular communications may experience kernel warnings and potential denial of service conditions when processing packets before the interface is fully initialized.

Affected Products

• Linux Kernel (multiple stable versions)
• Systems utilizing WiFi OCB mode for DSRC/V2X communications
• Embedded automotive and IoT systems with mac80211-based WiFi drivers

Discovery Timeline

• February 14, 2026 - CVE-2025-71224 published to NVD
• February 18, 2026 - Last updated in NVD database

Technical Details for CVE-2025-71224

Vulnerability Analysis

The vulnerability resides in the Linux kernel's mac80211 WiFi stack, specifically in the OCB (Outside the Context of a BSS) implementation. The ieee80211_ocb_rx_no_sta() function is designed to handle received packets from unknown stations in OCB mode. However, this function operates under the assumption that a valid channel context has already been established through a successful JOIN_OCB operation.

The core issue is a race condition where RX packet processing can occur before the OCB interface has completed its channel join procedure. When packets arrive during this initialization window, the function attempts to access the channel context which does not yet exist, resulting in kernel warnings being triggered in the RX path. This represents a time-of-check time-of-use (TOCTOU) pattern where the operational state of the interface is not properly validated before processing.

Root Cause

The root cause is insufficient state validation in the OCB RX path. The ieee80211_ocb_rx_no_sta() function fails to verify whether the OCB interface has successfully joined a channel before attempting to process incoming packets. The channel context, which is critical for proper packet handling, is only initialized after the JOIN_OCB command completes. Without a guard check for this state, early packet arrivals trigger operations on uninitialized data structures.

Attack Vector

This vulnerability is triggered through a race condition in the kernel's WiFi stack. While the attack vector is classified as unknown in the CVSS data, the vulnerability can be triggered when:

1. An OCB-capable WiFi interface is being initialized
2. External WiFi frames are received before the JOIN_OCB operation completes
3. The kernel attempts to process these frames through ieee80211_ocb_rx_no_sta()
4. The missing channel context causes warnings or errors in the RX processing path

The fix implements a check to skip RX peer handling when the OCB interface has not yet joined a channel, preventing the race condition from causing kernel warnings or instability.

Detection Methods for CVE-2025-71224

Indicators of Compromise

• Kernel warning messages related to ieee80211_ocb_rx_no_sta() in system logs
• Dmesg entries indicating null pointer or invalid context access in the mac80211 subsystem
• Unexpected WiFi interface behavior during OCB mode initialization
• System instability or crashes on devices using DSRC/V2X communications

Detection Strategies

• Monitor kernel logs for warnings originating from the mac80211 OCB subsystem
• Implement syslog monitoring rules to alert on ieee80211_ocb_rx_no_sta warnings
• Review dmesg output for WiFi-related kernel warnings during interface bring-up
• Deploy kernel tracing to monitor OCB interface state transitions

Monitoring Recommendations

• Enable verbose logging for WiFi subsystem events on affected systems
• Configure automated alerting for kernel warning patterns in centralized log management
• Monitor system stability metrics on devices utilizing OCB mode
• Establish baseline behavior for OCB interface initialization to detect anomalies

How to Mitigate CVE-2025-71224

Immediate Actions Required

• Update to a patched Linux kernel version containing the fix
• Review and apply the appropriate kernel patch from the provided stable branches
• Prioritize patching for systems using OCB mode in production environments
• Consider temporarily disabling OCB interfaces during maintenance windows until patched

Patch Information

The Linux kernel maintainers have released patches across multiple stable branches to address this vulnerability. The fix adds a state check to skip RX peer handling when the OCB interface has not yet completed the JOIN_OCB operation. The patches are available from the following kernel.org stable commits:

• Kernel Patch 536447521b3b
• Kernel Patch 8fd1c63e0168
• Kernel Patch b04c75366a54
• Kernel Patch e0bd226804f8
• Kernel Patch fcc768760df0
• Kernel Patch ff4071c60018
• Kernel Patch ffe1e19c3b0e

Workarounds

• Delay enabling RX on OCB interfaces until after JOIN_OCB completes at the application level
• Implement interface bring-up scripts that ensure proper initialization sequencing
• Consider disabling OCB mode if not required for operational needs
• Apply network-level filtering to reduce packet volume during interface initialization

# Example: Check current kernel version for patch status
uname -r

# Monitor for OCB-related kernel warnings
dmesg | grep -i "ocb\|mac80211"

# Check if OCB interfaces are in use
iw dev | grep -A5 "type OCB"