CVE-2026-43742: Apple Safari Use-After-Free Vulnerability

CVE-2026-43742 Overview

CVE-2026-43742 is a use-after-free vulnerability [CWE-416] affecting Apple Safari, iOS, iPadOS, and macOS Tahoe. Processing maliciously crafted web content can trigger the flaw, leading to an unexpected process crash. Apple addressed the issue with improved memory management in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2.

The vulnerability requires user interaction, such as visiting a malicious website. Exploitation impacts availability but does not directly compromise confidentiality or integrity based on the published CVSS metrics.

Critical Impact
Attackers hosting malicious web content can crash the browser process on unpatched Apple devices, disrupting availability across iPhone, iPad, and Mac endpoints.

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-2026-43742 published to NVD
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2026-43742

Vulnerability Analysis

CVE-2026-43742 is a use-after-free condition in the web content processing path used by Safari and the underlying WebKit engine on Apple operating systems. A use-after-free defect occurs when a program continues to reference memory after that memory has been released. The dangling reference then operates on data controlled by a subsequent allocation or on freed memory that no longer holds valid state.

Apple's advisory notes that the issue was addressed with improved memory management. Processing maliciously crafted web content can trigger the condition and lead to an unexpected process crash. The vulnerability is reachable over the network through standard web navigation but requires user interaction, such as loading an attacker-controlled page.

Root Cause

The root cause is improper lifetime management of an object during web content processing. Code paths retain and dereference a pointer after the underlying object has been freed. Apple's fix tightens allocation, retention, and release semantics for the affected object class to prevent the dangling reference.

Attack Vector

An attacker crafts a web page containing HTML, JavaScript, or media resources structured to trigger the freed-object access. Delivery mechanisms include phishing links, malicious advertisements, compromised sites, and embedded iframes. When a victim loads the content in a vulnerable browser or WebView, the WebKit process dereferences freed memory and crashes. Repeated exploitation can be used to interrupt browser sessions or disrupt applications that embed WebKit.

No verified public proof-of-concept code is available. See the Apple Support Article #127594, Apple Support Article #127595, and Apple Support Article #127685 for vendor technical details.

Detection Methods for CVE-2026-43742

Indicators of Compromise

Repeated Safari or WebKit-based application crashes correlated with visits to specific URLs or ad networks.
Crash reports in ~/Library/Logs/DiagnosticReports/ on macOS or device analytics on iOS referencing com.apple.WebKit.WebContent.
Unusual browser process termination events shortly after loading third-party embedded content.

Detection Strategies

Monitor endpoint telemetry for abnormal termination of WebContent, Safari, and other WebKit-hosted processes.
Correlate browser crash events with outbound HTTP(S) connections to newly observed or low-reputation domains.
Inspect proxy and DNS logs for user access to pages hosting obfuscated JavaScript or malformed media resources coincident with browser instability.

Monitoring Recommendations

Track OS and Safari build versions across the fleet to identify hosts still running versions earlier than 26.5.2.
Alert on repeated WebKit crash signatures from the same user within a short interval.
Ingest MDM compliance data into your SIEM to flag Apple devices missing the 26.5.2 update.

How to Mitigate CVE-2026-43742

Immediate Actions Required

Update to Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2 across all Apple endpoints.
Enforce update compliance through MDM policies and block non-compliant devices from sensitive resources.
Warn users against following untrusted links until patches are deployed.

Patch Information

Apple released fixes in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2. Refer to Apple Support Article #127594, Apple Support Article #127595, and Apple Support Article #127685 for build-specific guidance and download instructions.

Workarounds

Restrict browsing to trusted sites via web filtering or DNS-based reputation services until patches are applied.
Disable JavaScript for untrusted origins where operationally feasible.
Use content security policies and ad-blocking to reduce exposure to malicious third-party content.

bash

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

# Query macOS build version
sw_vers -productVersion

# Force MDM-managed update check (example using softwareupdate)
sudo softwareupdate --install --all --restart