CVE-2026-43726: Apple Safari Use-After-Free Vulnerability

CVE-2026-43726 Overview

CVE-2026-43726 is a use-after-free vulnerability [CWE-416] in Apple's web content processing stack affecting Safari, iOS, iPadOS, and macOS. Processing maliciously crafted web content triggers the flaw and can lead 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 is network-reachable and requires user interaction, such as visiting an attacker-controlled page. Impact is limited to availability, with no direct compromise of confidentiality or integrity reported by the vendor.

Critical Impact
A remote attacker can trigger an unexpected process crash on unpatched Apple devices by luring a user to malicious web content.

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-2026-43726 published to NVD
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2026-43726

Vulnerability Analysis

The flaw is a use-after-free condition in the web content processing path used by Safari and Apple's WebKit-based components. Apple's advisory states that processing maliciously crafted web content may lead to an unexpected process crash. The vendor resolved the issue with improved memory management, indicating that an object's lifetime was not correctly tracked during page rendering or script execution. Exploitation requires a user to load attacker-controlled content, such as a crafted HTML page, iframe, or web view embedded in an application.

Root Cause

Use-after-free vulnerabilities occur when code continues to reference memory that has already been freed. In this case, an object within the WebKit rendering pipeline is deallocated while another code path retains a dangling pointer to it. When that pointer is dereferenced, the process operates on invalid memory, producing a crash. Apple's remediation language ('addressed with improved memory management') is consistent with tightening object ownership or reference counting around the affected structure.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker hosts crafted web content on a domain, delivers it through a link, phishing message, ad network, or compromised site, and waits for a victim to render it. Any application embedding WebKit web views on affected Apple platforms is a potential trigger surface. Public exploitation has not been reported, and this CVE is not listed on the CISA Known Exploited Vulnerabilities catalog.

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

Detection Methods for CVE-2026-43726

Indicators of Compromise

Repeated crash reports referencing com.apple.WebKit.WebContent or Safari processes on endpoints running versions prior to 26.5.2.
Browser or web view sessions terminating immediately after loading specific external URLs or ad-served content.
Unusual ReportCrash diagnostic entries in ~/Library/Logs/DiagnosticReports/ correlated with recent web browsing activity.

Detection Strategies

Inventory Apple endpoints and flag any Safari, iOS, iPadOS, or macOS build below 26.5.2 as vulnerable.
Correlate endpoint crash telemetry for WebKit content processes with proxy logs to identify recurring malicious URLs.
Ingest macOS unified logs and iOS/iPadOS crash diagnostics into a central data lake to hunt for patterns of repeated WebContent termination.

Monitoring Recommendations

Alert on multiple WebKit content-process crashes on the same host within a short time window.
Monitor web proxy and DNS logs for user visits to newly registered or low-reputation domains preceding browser crashes.
Track MDM compliance reporting to confirm Safari and OS versions remain at or above 26.5.2 across the fleet.

How to Mitigate CVE-2026-43726

Immediate Actions Required

Update all affected devices to Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, or macOS Tahoe 26.5.2 as applicable.
Push the update through Mobile Device Management (MDM) to enforce timely patching across managed Apple endpoints.
Prioritize devices used to browse untrusted content or handle high-value accounts.

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 the specific advisories and download references.

Workarounds

Restrict browsing to trusted sites and block high-risk categories at the web proxy until patching completes.
Use alternative browsers on macOS for untrusted content where feasible, noting that other WebKit-based apps remain exposed.
Enable Lockdown Mode on iOS, iPadOS, and macOS for high-risk users to reduce the attack surface exposed to malicious web content.

bash

# Verify installed Safari version on macOS
mdls -name kMDItemVersion /Applications/Safari.app

# Check macOS build
sw_vers

# Trigger a software update check
softwareupdate --list
sudo softwareupdate --install --all --restart