CVE-2022-23088: FreeBSD Wi-Fi RCE Vulnerability

CVE-2022-23088 Overview

CVE-2022-23088 is a critical heap buffer overflow vulnerability in the FreeBSD operating system's IEEE 802.11 (Wi-Fi) beacon handling routine. The vulnerability exists in the processing of 802.11s Mesh ID elements, where the system fails to properly validate the length of the Mesh ID before copying it to a heap-allocated buffer.

When a FreeBSD Wi-Fi client is in scanning mode (not associated with an SSID), a malicious beacon frame can trigger an out-of-bounds write to kernel memory. This allows a remote, unauthenticated attacker within Wi-Fi range to potentially achieve remote code execution with kernel-level privileges.

Critical Impact

Remote code execution in kernel space through malicious Wi-Fi beacon frames, requiring no authentication and no user interaction—only physical proximity to the target system.

Affected Products

• FreeBSD 12.3 (through p4)
• FreeBSD 13.0 (all beta, RC, and patch releases through p10)
• FreeBSD 13.1 (beta releases b1-p1 and b2-p2)

Discovery Timeline

• 2024-02-15 - CVE-2022-23088 published to NVD
• 2025-06-04 - Last updated in NVD database

Technical Details for CVE-2022-23088

Vulnerability Analysis

This vulnerability represents a classic heap buffer overflow caused by insufficient bounds checking in the Wi-Fi subsystem. The 802.11 beacon handling routine parses incoming wireless frames to extract network information, including Mesh ID elements used in 802.11s mesh networking implementations.

The vulnerable code path is triggered when a FreeBSD system with an active Wi-Fi interface enters scanning mode—a common occurrence when the system searches for available networks. During this state, the Wi-Fi driver processes beacon frames from all nearby access points without requiring any prior association or authentication.

The attack is particularly dangerous because it can be executed remotely over the air by any attacker within Wi-Fi radio range. No user interaction is required, and the victim system does not need to be connected to any network—simply having Wi-Fi enabled and scanning for networks is sufficient to trigger the vulnerability.

Successful exploitation results in kernel memory corruption, which can be leveraged to achieve arbitrary code execution with ring-0 (kernel) privileges. This gives an attacker complete control over the compromised system, bypassing all user-space security mechanisms.

Root Cause

The root cause is a missing length validation in the IEEE 802.11s Mesh ID parsing routine. The code allocates a fixed-size heap buffer for storing the Mesh ID but does not verify that the incoming Mesh ID element length (as specified in the beacon frame) fits within the allocated buffer before performing the copy operation.

According to the IEEE 802.11s standard, a Mesh ID can be up to 32 bytes in length. However, the attacker can craft a malicious beacon frame claiming a Mesh ID length larger than expected, causing the copy operation to write beyond the allocated heap buffer boundaries into adjacent kernel memory structures.

Attack Vector

The attack is network-based (over Wi-Fi radio) and can be executed by an attacker who:

1. Is within Wi-Fi radio range of the target FreeBSD system
2. Can transmit malicious 802.11 beacon frames (using commodity Wi-Fi hardware in monitor/injection mode)
3. Waits for or triggers the target to enter Wi-Fi scanning mode

The attacker crafts a beacon frame with an oversized Mesh ID element. When the vulnerable FreeBSD system parses this beacon during a Wi-Fi scan, the heap buffer overflow occurs. By carefully controlling the overflow data, an attacker can corrupt adjacent heap metadata or kernel data structures to achieve code execution.

This vulnerability requires no authentication, no user interaction, and can affect systems that are merely scanning for Wi-Fi networks without being connected to any network.

Detection Methods for CVE-2022-23088

Indicators of Compromise

• Unexpected kernel crashes or panics on systems with Wi-Fi enabled, particularly during network scanning operations
• Anomalous Wi-Fi beacon frames with unusually large Mesh ID elements detected on network monitoring equipment
• Signs of kernel memory corruption or unexpected behavior following Wi-Fi scanning activity
• System instability when in proximity to untrusted wireless environments

Detection Strategies

• Monitor for kernel crash dumps that reference the Wi-Fi subsystem or 802.11 beacon processing functions
• Deploy wireless intrusion detection systems (WIDS) to identify malformed 802.11s Mesh ID beacon frames
• Implement endpoint detection and response (EDR) solutions capable of monitoring kernel-level anomalies
• Review system logs for unexpected Wi-Fi driver errors or kernel memory warnings

Monitoring Recommendations

• Enable kernel crash dump collection and analysis to identify potential exploitation attempts
• Monitor systems running affected FreeBSD versions in environments with untrusted Wi-Fi exposure
• Configure alerting for unexpected system reboots or kernel panics on FreeBSD Wi-Fi clients
• Review security advisories from FreeBSD for additional mitigation guidance

How to Mitigate CVE-2022-23088

Immediate Actions Required

• Update affected FreeBSD systems to patched versions immediately using freebsd-update or source-based updates
• If patching is not immediately possible, disable Wi-Fi interfaces on affected systems using ifconfig wlan0 down
• Unload Wi-Fi kernel modules on systems that do not require wireless connectivity
• Restrict physical access to environments where vulnerable systems operate to limit attacker proximity

Patch Information

FreeBSD has released security patches addressing this vulnerability as documented in FreeBSD Security Advisory FreeBSD-SA-22:07.wifi_meshid. System administrators should update to patched versions of FreeBSD 12.3, 13.0, or 13.1 that include the fix.

For systems using freebsd-update:

freebsd-update fetch
freebsd-update install

For systems built from source, apply the relevant patches and rebuild the kernel.

Workarounds

• Disable Wi-Fi functionality entirely on affected systems by unloading wireless driver modules
• Use wired Ethernet connections instead of Wi-Fi on critical systems until patches can be applied
• Implement network segmentation to isolate vulnerable systems from untrusted wireless environments
• Consider using external Wi-Fi adapters with separate driver stacks if wireless connectivity is required

# Disable Wi-Fi interface
ifconfig wlan0 down

# Unload Wi-Fi kernel modules
kldunload if_iwn  # Intel Wi-Fi
kldunload if_ath  # Atheros Wi-Fi

# Prevent Wi-Fi modules from loading at boot
# Add to /boot/loader.conf:
if_iwn_load="NO"
if_ath_load="NO"