CVE-2026-43731: Apple Safari Use-After-Free Vulnerability

CVE-2026-43731 Overview

CVE-2026-43731 is a use-after-free vulnerability [CWE-416] affecting Apple Safari, iOS, iPadOS, and macOS. Processing maliciously crafted web content triggers memory corruption in the browser engine. Apple addressed the flaw through improved memory management in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2.

The vulnerability is exploitable remotely over the network and requires user interaction, such as visiting an attacker-controlled webpage. Successful exploitation can lead to arbitrary code execution within the browser process context.

Critical Impact
Remote attackers can trigger memory corruption by luring users to malicious web content, potentially enabling arbitrary code execution across Safari, iOS, iPadOS, and macOS platforms.

Affected Products

Apple Safari (versions prior to 26.5.2)
Apple iOS and iPadOS (versions prior to 26.5.2)
Apple macOS Tahoe (versions prior to 26.5.2)

Discovery Timeline

2026-06-29 - CVE-2026-43731 published to NVD
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2026-43731

Vulnerability Analysis

CVE-2026-43731 is classified as a use-after-free condition [CWE-416] within the web content processing path shared by Safari and the underlying WebKit rendering stack. Use-after-free flaws occur when code continues to reference memory after it has been released, allowing an attacker to influence the contents of that freed region.

When the browser processes crafted HTML, JavaScript, or DOM manipulation sequences, an object reference persists beyond the object's lifetime. Subsequent access to that dangling pointer triggers memory corruption. Attackers can shape heap layouts to place controlled data where the freed object resided, converting the corruption into code execution primitives.

Root Cause

The root cause is improper lifetime management of an object referenced during web content processing. Apple's advisory states the fix improves memory management to ensure references are invalidated when the underlying object is released.

Attack Vector

The attack vector is network-based and requires user interaction. A victim must load attacker-controlled content, typically by visiting a malicious webpage, opening a crafted link, or rendering embedded web content inside another application that uses the system WebView.

Exploitation does not require prior authentication. Once triggered, the corruption impacts the Safari or WebKit-hosted process, giving attackers a foothold to attempt sandbox escape or chain additional vulnerabilities. No public proof-of-concept or exploit code is currently available. Refer to the Apple Support Article 127594 for vendor technical details.

Detection Methods for CVE-2026-43731

Indicators of Compromise

Unexpected Safari or WebKit process crashes with signatures consistent with heap corruption or freed-object access.
Diagnostic reports referencing com.apple.WebKit.WebContent faults following visits to untrusted URLs.
Outbound connections from browser child processes to previously unseen domains immediately after page loads.

Detection Strategies

Inventory endpoints running vulnerable Safari, iOS, iPadOS, or macOS versions and flag hosts not yet at 26.5.2.
Monitor crash telemetry from Safari and WebKit-hosted processes and correlate with recent browsing activity.
Inspect proxy and DNS logs for user visits to newly registered or low-reputation domains that could stage exploit content.

Monitoring Recommendations

Enable centralized collection of macOS unified logs and iOS crash reports to surface WebKit anomalies.
Alert on Safari child processes spawning shells, launching other binaries, or writing to unusual paths.
Track patch compliance for Safari 26.5.2 and the corresponding OS updates across managed devices.

How to Mitigate CVE-2026-43731

Immediate Actions Required

Update to Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2 on all affected devices.
Prioritize patching for high-risk users such as executives, developers, and administrators who browse externally.
Verify mobile device management (MDM) policies enforce the minimum OS versions containing the fix.

Patch Information

Apple released fixes in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2. See the Apple Support Article 127594, Apple Support Article 127595, and Apple Support Article 127685 for version details and release notes.

Workarounds

Restrict browsing to trusted domains through proxy filtering and DNS-based reputation blocking until patches are deployed.
Disable JavaScript for high-risk browsing sessions or use enterprise browser isolation to render untrusted content off-device.
Educate users to avoid clicking untrusted links delivered via email, messaging, or social platforms.

bash

# Verify Safari version on macOS
defaults read /Applications/Safari.app/Contents/Info.plist CFBundleShortVersionString

# Check macOS build to confirm 26.5.2 is installed
sw_vers