CVE-2026-43709: Apple Safari Use-After-Free Vulnerability

CVE-2026-43709 Overview

CVE-2026-43709 is a use-after-free vulnerability [CWE-416] affecting Apple Safari, iOS, iPadOS, and macOS Tahoe. The flaw resides in the web content processing engine and can be triggered when a user visits a page containing maliciously crafted content. Successful exploitation leads to an unexpected process crash, resulting in a denial-of-service condition against the browser or WebKit-based components. 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.

Critical Impact
Remote attackers can crash the browser process of any user who loads a malicious web page, disrupting availability of Safari and dependent WebKit-based applications across Apple 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-2026-43709 published to the National Vulnerability Database (NVD)
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2026-43709

Vulnerability Analysis

The vulnerability is a use-after-free condition in Apple's web content processing pipeline, tracked under [CWE-416]. Use-after-free issues occur when a program continues to reference memory after it has been freed, allowing attacker-influenced data to be interpreted as a live object. In this case, processing maliciously crafted web content triggers the freed-memory access and causes the rendering process to terminate unexpectedly.

According to Apple's advisories, the root fix involves improved memory management within the affected component. The EPSS score for this CVE is 0.24%, placing it in the 15.03 percentile for exploitation likelihood. No public proof-of-concept or in-the-wild exploitation has been reported at the time of publication.

Root Cause

The defect stems from improper lifecycle handling of an object referenced by the web content renderer. When specific DOM or scripting operations release the underlying allocation, dangling references remain reachable through subsequent operations. The renderer then dereferences freed memory, producing memory corruption that manifests as a process crash.

Attack Vector

Exploitation requires a victim to load attacker-controlled web content in Safari or any application that embeds WebKit. The attack vector is network-based and requires user interaction, such as clicking a link or visiting a compromised or malicious site. Impact is limited to availability - the vulnerability crashes the process but has no direct confidentiality or integrity effect per the CVSS metrics.

See the Apple security advisories for technical acknowledgements and component-level details: Apple Support Article 127594, Apple Support Article 127595, and Apple Support Article 127685.

Detection Methods for CVE-2026-43709

Indicators of Compromise

Repeated or unexplained Safari or WebKit process crashes (com.apple.WebKit.WebContent) recorded in system crash reporter logs.
Crash reports referencing use-after-free signatures, freed-object dereferences, or invalid pointer access within WebKit frames.
Outbound connections from user endpoints to newly registered or low-reputation domains immediately preceding a browser crash event.

Detection Strategies

Aggregate macOS and iOS crash logs into a central logging or SIEM platform and alert on clusters of WebKit content-process terminations across multiple users.
Correlate browser crash telemetry with URL and DNS resolution logs to identify the specific page that triggered the fault.
Monitor Safari and WebKit application versions across the fleet using MDM inventory data to identify hosts still running vulnerable builds prior to 26.5.2.

Monitoring Recommendations

Enable and forward macOS unified logs and iOS device management diagnostics so crash artifacts are retained for post-incident analysis.
Track web filtering and DNS logs for user visits to suspicious pages that coincide with rendering-process failures.
Baseline normal Safari crash rates per endpoint to make anomalous spikes easier to detect.

How to Mitigate CVE-2026-43709

Immediate Actions Required

Update Safari to version 26.5.2 on macOS endpoints and upgrade iOS and iPadOS devices to 26.5.2.
Upgrade macOS Tahoe hosts to the 26.5.2 release that ships the patched WebKit components.
Prioritize patching for users who routinely browse untrusted content or handle high-risk workflows such as executive communications or financial transactions.

Patch Information

Apple released fixes in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2. Patch details are documented in Apple Support Article 127594, Apple Support Article 127595, and Apple Support Article 127685. Deploy the updates through Apple Software Update, MDM configuration profiles, or Automated Device Enrollment policies.

Workarounds

Restrict browsing to trusted sites by enforcing web filtering or content-inspection proxies until patches are fully deployed.
Disable JavaScript for untrusted origins in Safari settings where feasible, reducing the attack surface for renderer-side memory corruption.
Use Lockdown Mode on high-risk iOS, iPadOS, and macOS devices to constrain WebKit features that expose complex parsing paths.

bash

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

# Verify iOS/iPadOS build via MDM query or on-device: Settings > General > About
# Ensure the version reported is 26.5.2 or later before considering the host remediated