CVE-2025-43359: Apple iPadOS DoS Vulnerability

CVE-2025-43359 Overview

CVE-2025-43359 is a logic vulnerability affecting Apple's state management in UDP socket handling across multiple operating systems. The flaw stems from improper state management where a UDP server socket bound to a specific local interface may inadvertently become bound to all network interfaces. This behavior could expose services that were intended to be accessible only on specific interfaces to a broader network attack surface.

Critical Impact

UDP server sockets intended for local-only access may become bound to all network interfaces, potentially exposing internal services to external network traffic and enabling unauthorized network access.

Affected Products

• Apple iOS and iPadOS (versions prior to iOS 18.7, iPadOS 18.7, iOS 26, and iPadOS 26)
• Apple macOS (versions prior to macOS Sonoma 14.8 and macOS Sequoia 15.7)
• Apple tvOS (versions prior to tvOS 26)
• Apple watchOS (versions prior to watchOS 26)
• Apple visionOS (versions prior to visionOS 26)

Discovery Timeline

• September 15, 2025 - CVE-2025-43359 published to NVD
• November 04, 2025 - Last updated in NVD database

Technical Details for CVE-2025-43359

Vulnerability Analysis

This vulnerability (CWE-670: Always-Incorrect Control Flow Implementation) exists within Apple's network stack state management for UDP sockets. When an application creates a UDP server socket and explicitly binds it to a specific local interface, the underlying state management logic fails to maintain this binding constraint under certain conditions. As a result, the socket may transition to being bound to all available interfaces (0.0.0.0 or ::), effectively bypassing the application's intended network isolation.

The issue is particularly concerning for applications that rely on interface-specific binding for security purposes, such as administrative services meant to be accessible only on loopback interfaces or internal network segments. The network-accessible nature of this vulnerability means that remote attackers could potentially reach services that developers intended to restrict to local-only access.

Root Cause

The root cause is a logic error in Apple's state management subsystem responsible for maintaining UDP socket binding states. The improper handling of state transitions allows the socket's binding configuration to change from a specific interface to all interfaces without proper validation or enforcement of the originally specified binding constraints.

Attack Vector

The vulnerability can be exploited over the network when a UDP service is incorrectly bound to all interfaces instead of the intended local interface. An attacker on an adjacent or remote network segment could:

1. Identify services that should be restricted to specific interfaces
2. Send UDP packets to the service on external interfaces that should not be listening
3. Interact with the service in ways the application developer did not intend to permit from external networks

The exploitation does not require authentication or user interaction, as the vulnerability affects the underlying socket binding behavior at the operating system level.

Detection Methods for CVE-2025-43359

Indicators of Compromise

• Unexpected network connections to UDP services from external IP addresses when those services should only be accessible locally
• UDP services responding on interfaces they were not explicitly configured to bind to
• Log entries showing traffic from external networks to services configured for local-only access
• Network scans revealing UDP ports open on all interfaces when application configuration specifies single-interface binding

Detection Strategies

• Monitor network traffic for UDP connections to internal services originating from unexpected network segments
• Implement periodic socket binding audits using tools like netstat or lsof to verify services are bound to intended interfaces
• Deploy network intrusion detection rules to alert on UDP traffic to sensitive services from untrusted networks
• Use application-level logging to track source addresses of incoming UDP connections and flag anomalies

Monitoring Recommendations

• Enable detailed network logging on Apple devices to capture UDP socket binding behavior
• Configure firewall rules to log and alert on UDP traffic reaching services that should be interface-restricted
• Implement endpoint detection and response (EDR) solutions to monitor for network exposure changes
• Regularly audit running services to ensure UDP sockets maintain their intended binding configurations

How to Mitigate CVE-2025-43359

Immediate Actions Required

• Update all Apple devices to the patched versions: iOS 18.7, iPadOS 18.7, iOS 26, iPadOS 26, macOS Sonoma 14.8, macOS Sequoia 15.7, tvOS 26, watchOS 26, or visionOS 26
• Audit all applications using UDP sockets to verify their current binding state matches the intended configuration
• Implement host-based firewall rules to block inbound UDP traffic on interfaces where services should not be accessible
• Review and restrict network access to Apple devices hosting sensitive UDP services

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. Organizations should prioritize applying these updates to all Apple devices in their environment. Detailed patch information is available in the following Apple Support articles:

• Apple Support Article #125108
• Apple Support Article #125109
• Apple Support Article #125111
• Apple Support Article #125112
• Apple Support Article #125114
• Apple Support Article #125115
• Apple Support Article #125116

Workarounds

• Configure host-based firewall rules (such as pf on macOS) to explicitly block inbound UDP traffic on unintended interfaces
• Implement network segmentation to limit exposure of vulnerable devices
• Use VPN or network access control to restrict which networks can reach Apple devices hosting UDP services
• Consider temporarily disabling UDP-based services that require interface-specific binding until patches can be applied

# macOS pf firewall example to restrict UDP access to specific interface
# Add to /etc/pf.conf and reload with: sudo pfctl -f /etc/pf.conf

# Block UDP traffic on external interfaces for local-only service (example port 5353)
block in quick on en0 proto udp from any to any port 5353
pass in quick on lo0 proto udp from any to any port 5353