CVE-2024-40782: Apple Safari Use-After-Free Vulnerability

CVE-2024-40782 Overview

CVE-2024-40782 is a use-after-free vulnerability affecting Apple's WebKit rendering engine across multiple Apple platforms and products. The vulnerability exists due to improper memory management when processing web content, which can be exploited by attackers to cause an unexpected process crash when a victim visits a maliciously crafted webpage.

This use-after-free condition occurs when WebKit continues to reference memory after it has been freed, creating a dangling pointer situation. When malicious web content triggers this condition, the browser process can crash, resulting in denial of service for affected users.

Critical Impact

Processing maliciously crafted web content may lead to an unexpected process crash, affecting availability across Apple's entire ecosystem including iOS, macOS, Safari, watchOS, tvOS, and visionOS devices.

Affected Products

• Apple Safari (versions prior to 17.6)
• Apple iOS and iPadOS (versions prior to 16.7.9 and 17.6)
• Apple macOS Sonoma (versions prior to 14.6)
• Apple watchOS (versions prior to 10.6)
• Apple tvOS (versions prior to 17.6)
• Apple visionOS (versions prior to 1.3)

Discovery Timeline

• July 2024 - Apple releases security patches addressing the vulnerability
• 2024-07-29 - CVE-2024-40782 published to NVD
• 2025-11-04 - Last updated in NVD database

Technical Details for CVE-2024-40782

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a memory corruption vulnerability class that occurs when a program continues to use a pointer after the memory it points to has been freed. In the context of WebKit, this type of vulnerability typically manifests during complex DOM operations, JavaScript execution, or rendering pipeline activities.

The attack requires user interaction—specifically, a victim must navigate to a malicious webpage hosting specially crafted content. Once the malicious content is processed by the vulnerable WebKit engine, it can trigger the use-after-free condition, causing the browser or application process to crash unexpectedly.

While the current impact is limited to denial of service (process crash), use-after-free vulnerabilities are particularly concerning in browser engines because they can potentially be chained with other techniques to achieve more severe impacts such as arbitrary code execution. However, no active exploitation has been observed in the wild, and this vulnerability is not currently listed in CISA's Known Exploited Vulnerabilities catalog.

Root Cause

The root cause of CVE-2024-40782 lies in improper memory management within WebKit. Specifically, the vulnerability occurs when memory is deallocated but references to that memory are not properly invalidated. When subsequent operations attempt to access this freed memory through stale pointers, it results in undefined behavior that manifests as a process crash.

Apple addressed this issue by implementing improved memory management techniques, ensuring that memory references are properly tracked and invalidated when the underlying memory is freed.

Attack Vector

The attack vector for this vulnerability is network-based, requiring user interaction. An attacker would need to:

1. Create a malicious webpage containing specially crafted web content designed to trigger the use-after-free condition
2. Deliver the malicious webpage to potential victims through phishing emails, malicious advertisements, compromised websites, or social engineering
3. Wait for victims to visit the malicious webpage using a vulnerable Apple browser or application
4. The malicious content is processed by WebKit, triggering the memory corruption and causing the process to crash

The vulnerability exploitation does not require any privileges on the target system, making it accessible to any attacker who can deliver malicious web content to victims.

Detection Methods for CVE-2024-40782

Indicators of Compromise

• Unexpected Safari, WebKit-based application, or system browser crashes while browsing the web
• Multiple browser process crashes in system logs with WebKit-related stack traces
• Crash reports indicating memory access violations or use-after-free conditions in WebKit components
• Anomalous network traffic patterns associated with known malicious domains delivering exploit payloads

Detection Strategies

• Monitor system crash logs for repeated WebKit or Safari process crashes with similar crash signatures
• Implement web traffic filtering to detect and block access to known malicious URLs or domains
• Deploy endpoint detection solutions capable of identifying exploitation attempts targeting browser vulnerabilities
• Configure browser crash reporting to centralize and analyze crash data for patterns indicating exploitation attempts

Monitoring Recommendations

• Enable detailed crash reporting on managed Apple devices to capture WebKit-related crashes
• Implement network-level monitoring to identify suspicious web content delivery patterns
• Review Apple device management (MDM) logs for patterns of browser instability across managed endpoints
• Correlate browser crash events with web browsing history to identify potentially malicious sites

How to Mitigate CVE-2024-40782

Immediate Actions Required

• Update all Apple devices to the latest patched versions: iOS/iPadOS 16.7.9 or 17.6, Safari 17.6, macOS Sonoma 14.6, watchOS 10.6, tvOS 17.6, and visionOS 1.3
• Enable automatic software updates on all Apple devices to ensure timely patch deployment
• Review and restrict web browsing on critical systems until patches can be applied
• Educate users about avoiding suspicious links and websites from untrusted sources

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. The patches implement improved memory management to prevent the use-after-free condition. Organizations should apply these updates immediately through their standard patch management processes.

Official security advisories are available from Apple:

• Apple Security Update HT214116 - Safari 17.6
• Apple Security Update HT214117 - iOS 17.6 and iPadOS 17.6
• Apple Security Update HT214119 - iOS 16.7.9 and iPadOS 16.7.9
• Apple Security Update HT214121 - macOS Sonoma 14.6
• Apple Security Update HT214122 - watchOS 10.6
• Apple Security Update HT214123 - tvOS 17.6
• Apple Security Update HT214124 - visionOS 1.3

Additionally, Debian LTS Announcement provides information for WebKitGTK users on Linux systems.

Workarounds

• Limit web browsing to trusted websites until patches can be applied
• Use content filtering or web proxy solutions to block access to potentially malicious content
• Consider using alternative browsers not based on WebKit for sensitive browsing activities
• Implement network segmentation to limit exposure of vulnerable devices to untrusted web content

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

# Check macOS version
sw_vers -productVersion

# Enable automatic updates on macOS via command line
sudo softwareupdate --schedule on

# List available software updates
softwareupdate --list