CVE-2025-43510

What is Apple's Shared Memory Model?

Apple's operating systems use shared memory regions to allow inter-process communication (IPC) between applications and the OS kernel or system daemons. These shared memory regions must be protected by proper locking mechanisms to prevent one process from corrupting another's memory during concurrent access. An improper locking vulnerability allows a malicious application to write to shared memory at a time when another process has not acquired the expected lock, causing unexpected memory state changes that can be exploited for privilege escalation.

Overview

CVE-2025-43510 is an improper locking vulnerability (CWE-667) affecting Apple watchOS, iOS, iPadOS, macOS, visionOS, and tvOS. A malicious application running on the device can exploit insufficient lock synchronization in shared memory management to cause unexpected memory changes shared between processes, enabling privilege escalation. The vulnerability is part of the "DarkSword" iOS exploit chain — a sophisticated multi-stage attack identified in early 2026. CISA added it to the KEV catalog on March 20, 2026 with a two-week deadline.

Affected Versions

Technical Details

The improper locking vulnerability (CWE-667) occurs in Apple's shared memory management subsystem. When multiple processes or threads access a shared memory region, proper synchronization (mutexes, semaphores, or equivalent) is required to prevent data races. The vulnerability arises from insufficient lock acquisition before accessing or modifying shared state — a window during which a malicious app can inject modified data into the shared memory region.

The attacker's app times its shared memory writes to coincide with the vulnerable window when the target process has not yet acquired the lock on the shared region. By placing controlled values into the shared memory, the attacker causes the target process (which may run with higher privileges) to operate on attacker-supplied data, enabling privilege escalation.

Key characteristics:

• Local attack vector — a malicious app must be installed and launched
• User interaction required (UI:R) — typically the user must run the malicious app
• Affects all major Apple OS platforms (iOS, macOS, watchOS, visionOS, tvOS)
• Part of the DarkSword exploit chain, which appears to be a mercenary spyware toolkit

Discovery

The vulnerability was identified as part of the DarkSword iOS exploit chain investigation. Specific reporter attribution has not been publicly disclosed by Apple.

Exploitation Context

CVE-2025-43510 was used as a privilege escalation step in the DarkSword iOS exploit chain — a sophisticated multi-stage spyware toolkit consistent with nation-state or mercenary spyware operations. CISA added it to the KEV catalog on March 20, 2026, with a tight 14-day deadline. The DarkSword chain targets high-value individuals (journalists, government officials, dissidents) and is consistent with the operational profile of commercial spyware vendors.

Remediation

1. Update all Apple devices immediately: iOS/iPadOS 18.7.2+, macOS Sequoia 15.7.2+, watchOS 26.1+, visionOS 26.1+, tvOS 26.1+. The CISA deadline was April 3, 2026.
2. Apply updates across all Apple platforms — the vulnerability affects every Apple OS; a patched iPhone but unpatched Apple Watch still represents a compromise vector.
3. Enable Lockdown Mode on devices used by high-risk individuals (journalists, government officials, executives) — this mode significantly reduces the attack surface for spyware chains.
4. Enable automatic updates on all managed Apple devices to ensure future zero-day patches are applied promptly.
5. Review installed apps for unexpected or unfamiliar apps that could serve as spyware delivery vehicles.