CVE-2024-40856: Apple iPadOS DOS Vulnerability

CVE-2024-40856 Overview

CVE-2024-40856 is an integrity issue affecting Apple's wireless networking stack across iOS, iPadOS, macOS, and tvOS. The vulnerability allows a network-adjacent attacker to force an affected device to disconnect from a secure Wi-Fi network. Apple addressed the issue by strengthening Beacon Protection in iOS 18, iPadOS 18, macOS Sequoia 15, and tvOS 18.

The flaw resides in how affected devices validate Wi-Fi beacon frames, enabling availability impact without requiring authentication or user interaction. While the issue does not expose data or permit code execution, it can be used to disrupt connectivity for targeted devices on protected wireless networks.

Critical Impact
An attacker within wireless range can force devices to disconnect from a secure network, disrupting connectivity and potentially enabling downstream attacks against reconnection.

Affected Products

Apple iOS (prior to iOS 18)
Apple iPadOS (prior to iPadOS 18)
Apple macOS (prior to macOS Sequoia 15)
Apple tvOS (prior to tvOS 18)

Discovery Timeline

2024-09-17 - CVE-2024-40856 published to NVD
2026-04-02 - Last updated in NVD database

Technical Details for CVE-2024-40856

Vulnerability Analysis

The vulnerability stems from insufficient integrity validation of Wi-Fi beacon frames received by Apple devices. Beacon frames are management frames broadcast by access points to announce their presence and synchronize clients. Without proper authentication of these frames, an attacker can craft malicious beacons that the client device treats as legitimate.

Apple's fix introduces Beacon Protection, an 802.11 mechanism that uses Beacon Integrity Group Temporary Key (BIGTK) and Beacon Integrity Protocol (BIP) to authenticate beacon contents. The pre-patch behavior accepted unprotected or improperly validated beacons, enabling adversaries to inject forged frames that triggered client-side state changes.

Exploitation results in a denial of service on the wireless connection. The attacker does not gain access to encrypted traffic, but disconnection events can be chained with rogue access point attacks to coerce reconnection to attacker-controlled infrastructure.

Root Cause

The root cause is missing or insufficient cryptographic integrity verification of 802.11 beacon frames. Affected devices accepted spoofed beacon parameters without confirming they originated from the legitimate access point, leaving clients vulnerable to forced disassociation.

Attack Vector

The attack is network-based and requires the adversary to be within wireless range of the targeted device. The attacker transmits crafted beacon frames impersonating the legitimate access point. No authentication or user interaction is required. Successful exploitation forces the target device to disconnect from the secure network.

No verified public proof-of-concept exploit is currently available. For protocol-level details, see Full Disclosure List #32, Full Disclosure List #33, and Full Disclosure List #34.

Detection Methods for CVE-2024-40856

Indicators of Compromise

Unexpected Wi-Fi disconnection events on Apple devices running pre-iOS 18, pre-iPadOS 18, pre-macOS Sequoia 15, or pre-tvOS 18 builds.
Anomalous 802.11 beacon frames with spoofed BSSIDs matching trusted access points within the wireless environment.
Repeated client reassociation attempts shortly after broadcast frame anomalies.

Detection Strategies

Deploy wireless intrusion detection systems (WIDS) capable of identifying beacon spoofing and management frame anomalies.
Correlate endpoint disconnection logs from MDM telemetry with wireless infrastructure events to spot patterns of forced disassociation.
Monitor enterprise access points for clients running outdated Apple OS builds that lack Beacon Protection support.

Monitoring Recommendations

Enable 802.11w Management Frame Protection (MFP) and Beacon Protection on enterprise wireless infrastructure where supported.
Track Apple OS version inventory through endpoint management to identify devices still exposed to CVE-2024-40856.
Review wireless controller logs for beacon integrity check failures and unexpected BSSID transitions.

How to Mitigate CVE-2024-40856

Immediate Actions Required

Update affected devices to iOS 18, iPadOS 18, macOS Sequoia 15, or tvOS 18 or later.
Enforce OS update compliance through mobile device management (MDM) policies across the Apple device fleet.
Enable Beacon Protection and 802.11w Management Frame Protection on enterprise wireless infrastructure.

Patch Information

Apple released fixes in iOS 18, iPadOS 18, macOS Sequoia 15, and tvOS 18. Refer to the official advisories: Apple Security Update #121238, Apple Security Update #121248, and Apple Security Update #121250.

Workarounds

Restrict use of unpatched Apple devices on critical wireless networks until updates are applied.
Use wired connectivity for high-value workflows where wireless disruption presents operational risk.
Segment guest and corporate wireless networks to limit attacker proximity to protected SSIDs.

bash

# Verify Apple device OS version against patched builds
# macOS
sw_vers -productVersion

# iOS/iPadOS (via MDM query or Settings > General > About)
# Confirm version is 18.0 or later