CVE-2025-43342: Apple Safari DOS Vulnerability

CVE-2025-43342 Overview

CVE-2025-43342 is an input validation vulnerability affecting Apple's WebKit rendering engine used across multiple Apple platforms and open-source WebKit implementations. The flaw stems from a correctness issue in the web content processing logic that allows maliciously crafted web content to trigger an unexpected process crash. This vulnerability impacts a wide range of Apple devices including iPhones, iPads, Macs, Apple Watch, Apple TV, and Vision Pro, as well as third-party implementations like WebKitGTK and WPE WebKit.

Critical Impact

Attackers can exploit this vulnerability remotely by delivering malicious web content to vulnerable devices, potentially causing denial of service conditions through process crashes. The network-accessible nature with no authentication requirements makes this particularly dangerous for targeted attacks.

Affected Products

• Apple Safari (versions prior to Safari 26)
• Apple iOS and iPadOS (versions prior to iOS 26/iPadOS 26 and iOS 18.7/iPadOS 18.7)
• Apple macOS (affected versions)
• Apple tvOS (versions prior to tvOS 26)
• Apple watchOS (versions prior to watchOS 26)
• Apple visionOS (versions prior to visionOS 26)
• WebKitGTK (affected versions)
• WPE WebKit (affected versions)

Discovery Timeline

• September 15, 2025 - CVE-2025-43342 published to NVD
• November 20, 2025 - Last updated in NVD database

Technical Details for CVE-2025-43342

Vulnerability Analysis

This vulnerability is classified under CWE-20 (Improper Input Validation), indicating that the WebKit engine fails to properly validate certain inputs when processing web content. The improper validation allows attackers to craft malicious web content that, when rendered by the WebKit engine, triggers unexpected behavior leading to a process crash.

The vulnerability exists in the core web content processing mechanisms of WebKit, which is shared across Safari and embedded browser implementations on Apple platforms. When a user visits a malicious webpage or an application renders attacker-controlled web content, the flawed validation logic can be exploited to destabilize the rendering process.

The attack can be executed remotely over the network without requiring any user authentication or special privileges, making it particularly accessible to attackers. The impact extends to confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause is a correctness issue in WebKit's input validation checks when processing web content. The insufficient validation allows malformed or specially crafted content to bypass security checks and trigger abnormal processing states, ultimately resulting in process termination. Apple addressed this by implementing improved checks in the content processing pipeline.

Attack Vector

The attack vector is network-based, requiring an attacker to deliver malicious web content to a victim. This can be accomplished through several methods:

1. Direct Navigation - Tricking users into visiting a malicious website hosting the exploit content
2. Embedded Content - Injecting malicious content into legitimate websites through advertising networks, compromised third-party scripts, or XSS vulnerabilities
3. Application WebViews - Targeting applications that use WebKit to render user-controlled or external content
4. Email/Messaging - Sending links to malicious content through email or messaging platforms

The exploit requires no user interaction beyond the initial navigation or content rendering, and no authentication is necessary for successful exploitation.

Detection Methods for CVE-2025-43342

Indicators of Compromise

• Unexpected Safari, WebKit, or WebView process crashes on Apple devices
• Repeated crash logs in system diagnostics pointing to WebKit content rendering
• User reports of browser or app crashes when visiting specific websites
• Unusual patterns of network requests preceding application crashes

Detection Strategies

• Monitor system crash logs for WebKit-related process terminations with patterns consistent with malicious content processing
• Implement network monitoring to identify requests to known malicious domains serving exploit content
• Deploy endpoint detection solutions capable of correlating browser crashes with suspicious network activity
• Review application telemetry for abnormal crash rates in WebKit-powered components

Monitoring Recommendations

• Enable enhanced logging for Safari and WebKit processes across managed Apple devices
• Configure SIEM rules to alert on clusters of WebKit-related crashes from organizational devices
• Monitor threat intelligence feeds for emergence of active exploitation or proof-of-concept code
• Track Apple security advisories and WebKit security mailing lists for related vulnerability disclosures

How to Mitigate CVE-2025-43342

Immediate Actions Required

• Update all Apple devices to the latest patched versions: Safari 26, iOS 26/iPadOS 26, iOS 18.7/iPadOS 18.7, tvOS 26, watchOS 26, and visionOS 26
• Update WebKitGTK and WPE WebKit installations to patched versions
• Enable automatic updates on all Apple devices to receive future security patches promptly
• Review and restrict access to untrusted web content on critical systems where immediate patching is not possible

Patch Information

Apple has released patches addressing this vulnerability across multiple products. Security updates are available through the following Apple Security Advisories:

• Apple Security Advisory #125108
• Apple Security Advisory #125109
• Apple Security Advisory #125113
• Apple Security Advisory #125114
• Apple Security Advisory #125115
• Apple Security Advisory #125116

Updates can be applied through System Settings on macOS, Settings app on iOS/iPadOS, and respective update mechanisms on tvOS, watchOS, and visionOS devices.

Workarounds

• Use alternative browsers not based on WebKit on macOS systems while awaiting patch deployment
• Implement web content filtering to block access to known malicious sites
• Consider disabling JavaScript on untrusted sites as a temporary risk reduction measure
• Restrict WebView usage in enterprise applications until devices are patched

# Verify Safari version on macOS
/Applications/Safari.app/Contents/MacOS/Safari --version

# Check iOS/iPadOS version via MDM query or device Settings > General > About
# Ensure devices report iOS 26+, iOS 18.7+, or later patched versions