CVE-2025-31238: Apple Safari Buffer Overflow Vulnerability

CVE-2025-31238 Overview

CVE-2025-31238 is a memory corruption vulnerability affecting Apple's WebKit rendering engine across multiple Apple platforms. The vulnerability stems from improper bounds checking (CWE-119) when processing web content, potentially allowing attackers to corrupt memory through maliciously crafted web pages. This network-accessible vulnerability requires no user interaction or authentication, making it particularly concerning for organizations with Apple device deployments.

Critical Impact

Processing maliciously crafted web content may lead to memory corruption, potentially enabling attackers to execute arbitrary code or cause application crashes across Safari, iOS, macOS, and other Apple platforms.

Affected Products

• Apple Safari versions prior to 18.5
• Apple iOS and iPadOS versions prior to 18.5
• Apple macOS Sequoia versions prior to 15.5
• Apple tvOS versions prior to 18.5
• Apple visionOS versions prior to 2.5
• Apple watchOS versions prior to 11.5

Discovery Timeline

• May 12, 2025 - CVE-2025-31238 published to NVD
• April 2, 2026 - Last updated in NVD database

Technical Details for CVE-2025-31238

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), indicating that WebKit fails to properly validate boundaries when processing certain web content. Memory corruption vulnerabilities of this type occur when software does not properly restrict read or write operations to the intended memory buffer, allowing data to be written to adjacent memory locations.

The network-based attack vector means exploitation can occur remotely through a web browser without requiring any prior access or special privileges. The lack of user interaction requirements makes this vulnerability particularly dangerous, as simply loading a malicious webpage could trigger the exploit.

Root Cause

The root cause lies in insufficient input validation within WebKit's content processing routines. When handling maliciously crafted web content, the engine fails to properly verify memory bounds before performing operations, leading to potential buffer overflows or out-of-bounds memory access. Apple addressed this issue with improved checks in the affected components.

Attack Vector

Exploitation of CVE-2025-31238 follows a network-based attack pattern:

1. An attacker creates a malicious website containing specially crafted web content designed to trigger the memory corruption
2. A victim visits the malicious webpage using a vulnerable version of Safari or an app utilizing WebKit
3. The WebKit engine processes the malicious content without proper bounds validation
4. Memory corruption occurs, potentially allowing arbitrary code execution or causing a denial of service

The vulnerability requires no authentication and no user interaction beyond visiting a malicious webpage, significantly lowering the barrier for exploitation.

Detection Methods for CVE-2025-31238

Indicators of Compromise

• Unexpected Safari or WebKit-based application crashes when visiting unknown websites
• Abnormal memory consumption patterns in Safari or WKWebView processes
• System logs showing WebKit process crashes with memory-related error codes
• Unusual network connections initiated by Safari or WebKit processes following page loads

Detection Strategies

• Monitor for anomalous WebKit process behavior including unexpected crashes or high memory usage
• Implement web filtering to block access to known malicious domains serving exploit code
• Deploy endpoint detection and response (EDR) solutions capable of detecting memory corruption attempts
• Review system crash logs for patterns consistent with memory corruption in WebKit components

Monitoring Recommendations

• Enable detailed logging for Safari and WebKit-based applications
• Monitor for repeated application crashes that may indicate exploitation attempts
• Track network traffic for connections to suspicious or newly registered domains
• Implement SentinelOne's behavioral AI to detect exploitation patterns in real-time

How to Mitigate CVE-2025-31238

Immediate Actions Required

• Update all Apple devices to the latest available software versions immediately
• Prioritize patching Safari 18.5, iOS 18.5, iPadOS 18.5, macOS Sequoia 15.5, tvOS 18.5, visionOS 2.5, and watchOS 11.5
• Enable automatic updates on all Apple devices to receive future security patches promptly
• Consider using web content filtering to reduce exposure to potentially malicious websites

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. Organizations should apply the following updates:

• Safari 18.5 - See Apple Support Document #122404
• iOS and iPadOS 18.5 - See Apple Support Document #122716
• macOS Sequoia 15.5 - See Apple Support Document #122719
• tvOS 18.5 - See Apple Support Document #122720
• visionOS 2.5 - See Apple Support Document #122721
• watchOS 11.5 - See Apple Support Document #122722

Additional technical details are available on the Full Disclosure mailing list archives.

Workarounds

• Use alternative browsers on macOS where possible until Safari can be updated
• Implement network-level web filtering to block known malicious sites
• Restrict access to untrusted websites through MDM policies for managed devices
• Consider disabling JavaScript in Safari settings as a temporary measure (note: this will impact website functionality)

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

# Check for available macOS updates
softwareupdate --list

# Install all available updates
softwareupdate --install --all