CVE-2025-43520 — Apple Multi-Platform Classic Buffer Overflow

Affected Products: Apple watchOS, iOS, iPadOS, macOS, visionOS, tvOS Vulnerability Type: Classic Buffer Overflow (CWE-120) Attack Vector: Local — requires execution of a malicious application CISA KEV Patch Deadline: April 3, 2026 (federal agencies)

Technical Description

CVE-2025-43520 is a classic buffer overflow vulnerability present across six Apple operating systems: watchOS, iOS, iPadOS, macOS, visionOS, and tvOS. The flaw exists at the kernel level and can be triggered by a malicious application running on the affected device.

A buffer overflow at kernel privilege enables two distinct outcomes: arbitrary kernel memory writes or forced system termination. Kernel memory writes are the more severe outcome — an attacker who achieves this primitive can manipulate kernel data structures, bypass memory protections, escalate privileges, or establish persistent footholds on compromised hardware.

The attack vector is local. An attacker cannot exploit this flaw remotely over a network without a separate initial access primitive. Exploitation requires the target to run a malicious application on the device, which places this vulnerability in a category commonly abused through malicious App Store submissions, sideloaded applications, or apps delivered via enterprise distribution profiles.

Affected Surface

The scope of affected platforms is broad. Apple's six primary operating systems share underlying frameworks and kernel code, which explains why a single buffer overflow manifests across:

  • iOS and iPadOS — iPhones and iPads used by enterprise employees, executives, and government personnel
  • macOS — Macs used across enterprise and government environments
  • watchOS — Apple Watch devices, which often have access to health and notification data
  • tvOS — Apple TV devices, which may operate on internal networks
  • visionOS — Apple Vision Pro, a platform with access to spatial and environmental sensor data

Any organization running unpatched Apple devices across these platforms carries exposure.

Real-World Impact

Kernel memory corruption vulnerabilities are high-value targets for privilege escalation chains. Attackers who achieve local code execution — through phishing, malicious app delivery, or supply chain compromise — routinely chain that access with a kernel-level flaw to fully compromise the device.

On iOS and iPadOS, a successful kernel write can bypass Pointer Authentication Codes (PAC) and other hardware mitigations when combined with additional exploitation techniques. On macOS, kernel memory corruption can disable System Integrity Protection (SIP) mechanisms or install persistent kernel extensions.

CISA added CVE-2025-43520 to its Known Exploited Vulnerabilities (KEV) catalog, mandating that U.S. federal agencies patch by April 3, 2026. Inclusion in the KEV catalog reflects confirmed exploitation activity or a high-confidence assessment of active abuse.

Organizations in defense, finance, healthcare, and government sectors that deploy Apple hardware at scale face the highest operational risk. Mobile device management (MDM) environments where users can install applications outside of strict allow-lists expand the exploitable surface significantly.

Exploitation Requirements

Successful exploitation requires:

  1. A malicious application executing on the target device
  2. Sufficient application permissions to trigger the vulnerable code path
  3. An unpatched version of the affected operating system

Remote exploitation without a separate delivery mechanism is not possible based on current technical analysis.

Patching and Mitigation Guidance

Primary remediation: Install the latest available OS versions from Apple. Apple published security updates addressing CVE-2025-43520 across all affected platforms. Organizations should consult Apple's security releases page for specific version numbers.

MDM-managed environments: Push OS update enforcement policies immediately. Use MDM solutions (Jamf, Microsoft Intune, Apple Business Manager) to require minimum OS versions on all enrolled devices. Devices that fail to update within a defined window should be quarantined from corporate resources.

Application control: Restrict application installation to managed, vetted sources. Disable sideloading and enterprise distribution profile installation where operationally feasible. Review and audit installed applications on managed devices for unauthorized or suspicious entries.

watchOS and tvOS: These platforms are frequently overlooked in patch cycles. Include all Apple device categories in your asset inventory and update enforcement policies — not just iPhones and Macs.

visionOS: Apple Vision Pro deployments are limited but growing in enterprise pilots. Ensure these devices are enrolled in MDM and subject to the same update enforcement as other Apple hardware.

Federal agencies must meet the CISA April 3, 2026 deadline. Commercial organizations should treat that date as a maximum threshold, not a target — patch now.

CVE-2025-43520 is tracked in the CISA Known Exploited Vulnerabilities catalog. Monitor Apple's security advisories for additional technical detail as the disclosure matures.