CVE-2025-43529: Apple Safari Use-After-Free Vulnerability

CVE-2025-43529 Overview

CVE-2025-43529 is a use-after-free vulnerability affecting Apple's WebKit rendering engine across multiple Apple operating systems and Safari browser. The vulnerability stems from improper memory management that can be triggered when processing maliciously crafted web content. Successful exploitation allows attackers to achieve arbitrary code execution on vulnerable devices.

Apple has confirmed that this vulnerability has been actively exploited in the wild as part of an "extremely sophisticated attack against specific targeted individuals" on iOS versions prior to iOS 26. This designation indicates the vulnerability was likely used in targeted surveillance or espionage operations. The vulnerability is also tracked alongside CVE-2025-14174, which was issued in response to the same report.

Critical Impact

This use-after-free vulnerability is actively exploited in sophisticated targeted attacks and enables remote code execution through malicious web content. CISA has added this to the Known Exploited Vulnerabilities catalog.

Affected Products

• Apple Safari versions prior to 26.2
• Apple iOS versions prior to 18.7.3 and 26.2
• Apple iPadOS versions prior to 18.7.3 and 26.2
• Apple macOS Tahoe versions prior to 26.2
• Apple watchOS versions prior to 26.2
• Apple tvOS versions prior to 26.2
• Apple visionOS versions prior to 26.2

Discovery Timeline

• 2025-12-17 - CVE-2025-43529 published to NVD
• 2025-12-18 - Last updated in NVD database

Technical Details for CVE-2025-43529

Vulnerability Analysis

CVE-2025-43529 (CWE-416: Use After Free) is a memory corruption vulnerability within Apple's WebKit engine. Use-after-free vulnerabilities occur when an application continues to use a pointer after the memory it references has been freed. In this case, the vulnerability exists in how WebKit handles certain objects during web content processing.

The attack requires user interaction—specifically, a victim must visit a malicious webpage or view malicious web content. Once triggered, the use-after-free condition can corrupt memory in a way that allows attackers to execute arbitrary code within the context of the vulnerable application or process. Given WebKit's deep integration across Apple's ecosystem, successful exploitation could provide attackers with significant access to compromised devices.

The fact that Apple explicitly mentions this was used in "extremely sophisticated" attacks against "specific targeted individuals" strongly suggests this vulnerability was leveraged by advanced threat actors, potentially nation-state groups, for surveillance purposes. Such attacks typically combine multiple vulnerabilities to achieve complete device compromise.

Root Cause

The root cause of CVE-2025-43529 is improper memory management within WebKit. When certain web content is processed, WebKit may free a memory object while retaining a pointer to that memory. Subsequent operations that reference this dangling pointer can lead to memory corruption. Apple addressed this through improved memory management to ensure proper object lifecycle handling.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker must craft malicious web content and deliver it to a target through various means:

• Hosting the malicious content on a compromised or attacker-controlled website
• Embedding malicious content in advertisements (malvertising)
• Sending links to malicious content via phishing emails or messages
• Injecting malicious content through man-in-the-middle attacks on non-HTTPS traffic

When the victim's browser renders the malicious content, the use-after-free condition is triggered, potentially allowing the attacker to execute arbitrary code with the privileges of the rendering process.

The vulnerability affects WebKit across all Apple platforms, meaning a single exploit could potentially target iPhones, iPads, Macs, Apple Watches, Apple TVs, and Vision Pro devices.

Detection Methods for CVE-2025-43529

Indicators of Compromise

• Unexpected WebKit or Safari crashes, particularly when visiting unknown websites
• Suspicious process spawning from Safari, WebKit, or related processes
• Unusual network connections originating from browser processes
• Evidence of memory corruption or abnormal memory allocation patterns in system logs

Detection Strategies

• Monitor for anomalous behavior in WebKit-based processes including Safari and embedded web views
• Deploy endpoint detection and response (EDR) solutions capable of identifying exploit patterns and post-exploitation activity
• Analyze crash reports for signatures consistent with use-after-free exploitation attempts
• Implement network monitoring to detect connections to known malicious infrastructure

Monitoring Recommendations

• Enable detailed logging for Safari and WebKit components where supported
• Configure mobile device management (MDM) solutions to report on OS and browser version compliance
• Monitor for rapid OS updates being pushed by Apple, which may indicate active exploitation
• Track CISA KEV catalog updates for related vulnerabilities in the same attack chain

How to Mitigate CVE-2025-43529

Immediate Actions Required

• Update all Apple devices to the latest patched versions immediately: iOS 18.7.3 or iOS 26.2, iPadOS 18.7.3 or iPadOS 26.2, macOS Tahoe 26.2, Safari 26.2, watchOS 26.2, tvOS 26.2, and visionOS 26.2
• Prioritize updates for devices belonging to high-risk individuals such as executives, journalists, activists, or government personnel
• Review CISA KEV catalog requirements and ensure compliance with federal mandates if applicable
• Conduct inventory of all Apple devices in the enterprise environment to verify patch status

Patch Information

Apple has released security updates addressing CVE-2025-43529 across all affected platforms. Detailed patch information is available in the following security advisories:

• Apple Security Advisory #125884
• Apple Security Advisory #125885
• Apple Security Advisory #125886
• Apple Security Advisory #125889
• Apple Security Advisory #125890
• Apple Security Advisory #125891
• Apple Security Advisory #125892

This vulnerability is listed in the CISA Known Exploited Vulnerabilities Catalog, which mandates federal agencies apply patches within specified timeframes.

Workarounds

• Avoid clicking links from unknown or untrusted sources until patches can be applied
• Consider using Lockdown Mode on iOS devices for high-risk individuals, which reduces the attack surface by limiting certain WebKit features
• Implement web filtering to block access to known malicious domains
• Use network segmentation to isolate devices that cannot be immediately patched

# Verify iOS/iPadOS version via MDM query or device inspection
# Ensure devices report version 18.7.3+ or 26.2+
# For macOS, verify Tahoe 26.2 or later is installed

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

# Enable automatic updates on macOS
sudo softwareupdate --schedule on