CVE-2026-43703: Apple Memory Handling Vulnerability in iOS, macOS, tvOS

Technical summary

This vulnerability stems from improper memory handling in web content processing, falling under both out-of-bounds read (CWE-125) and out-of-bounds write (CWE-787) categories. The flaw permits a remote, unauthenticated attacker to trigger an unexpected process termination by crafting malicious web content that exploits the memory boundary conditions. The CVSS 3.1 score of 6.5 (MEDIUM) reflects the requirement for user interaction and the availability-only impact (no confidentiality or integrity breach).

Business impact

Organizations with significant Apple device deployments face service disruption risk if users encounter malicious web content, particularly in sectors relying on continuous mobile or desktop productivity. The attack vector is the public internet with no privilege escalation required, making it broadly reachable. However, the impact is limited to denial of service rather than data theft or system compromise. Depending on enterprise reliance on specific affected applications, patching timeline should balance disruption risk against deployment complexity.

Affected systems

Apple iOS 26.5.1 and earlier, iPadOS 26.5.1 and earlier, macOS Sequoia 15.7.7 and earlier, macOS Sonoma 14.8.7 and earlier, macOS Tahoe 26.5.1 and earlier, tvOS 26.5 and earlier, visionOS 26.5 and earlier, and watchOS 26.5 and earlier. Any device running these versions and processing web content is potentially vulnerable; this includes Safari usage and any embedded web views in third-party applications.

Exploitability

This vulnerability requires user interaction—specifically, the user must view or interact with malicious web content. No exploit has been added to CISA's Known Exploited Vulnerabilities (KEV) catalog as of the latest data, and no public proof-of-concept has been widely disclosed. The barrier to exploitation is low from a technical standpoint (only network access and malformed input), but the practical requirement for user engagement moderates the risk. Attackers could embed the payload in compromised websites, advertisements, or social engineering campaigns.

Remediation

Apply the security updates: iOS 26.5.2, iPadOS 26.5.2, macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, macOS Tahoe 26.5.2, tvOS 26.6, visionOS 26.6, and watchOS 26.6. Organizations should prioritize devices used for critical workflows or those exposed to untrusted internet content. Stagger deployment if infrastructure constraints exist, but complete deployment within standard patch cycles (typically 30 days for MEDIUM-severity issues).

Patch guidance

Download and install the latest OS versions from Apple's official Software Update channels. For macOS, use System Settings > General > Software Update. For iOS and iPadOS, navigate to Settings > General > Software Update. Enterprise deployments should use Mobile Device Management (MDM) to automate and enforce deployment across managed fleets. Verify successful installation by confirming the OS build number matches the patched version in device settings. No special configuration or reboot sequencing is required beyond standard OS update procedures.

Detection guidance

Monitor for unexpected crashes or service interruptions in web browsers and apps that process web content. If feasible, review crash logs on managed devices for memory-related faults occurring during web navigation. Network-level detection is limited since the attack vector is malicious web content; focus detection on client-side telemetry and device health monitoring. Endpoint Detection and Response (EDR) solutions on macOS can flag unusual memory access patterns if they support OS-level memory instrumentation.

Why prioritize this

Although rated MEDIUM severity with no known active exploitation, the broad reach (six OS families), ease of triggering (user clicks a link), and prevalence of web browsing in typical organizations warrant timely patching. The lack of KEV listing suggests this is not yet weaponized at scale, providing a window to deploy updates before threat actors develop practical exploits. For organizations with heavy iOS/macOS populations, this should be prioritized in the standard monthly patch cycle.

Risk score, explained

The CVSS 3.1 base score of 6.5 reflects an attack requiring network accessibility and user interaction, with impact limited to availability (process crash). The score does not account for ease of social engineering or the prevalence of the affected software—those are organizational factors for risk scoring. The absence of confidentiality and integrity impact caps the severity, despite the wide attack surface. Organizations may adjust their internal risk rating upward if web browsing isolation or user training is insufficient.

Frequently asked questions