CVE-2025-31257: Apple Safari DOS Vulnerability

CVE-2025-31257 Overview

CVE-2025-31257 is a memory handling vulnerability affecting Apple Safari and WebKit-based applications across multiple Apple platforms. The flaw exists in how the browser processes web content, where maliciously crafted content can trigger improper memory operations leading to an unexpected Safari crash. This vulnerability falls under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), indicating potential buffer boundary violations during content processing.

Critical Impact

Processing maliciously crafted web content may cause Safari to crash unexpectedly, resulting in denial of service for users browsing compromised or malicious websites.

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 watchOS versions prior to 11.5
• Apple tvOS versions prior to 18.5
• Apple visionOS versions prior to 2.5

Discovery Timeline

• May 12, 2025 - CVE-2025-31257 published to NVD
• November 3, 2025 - Last updated in NVD database

Technical Details for CVE-2025-31257

Vulnerability Analysis

This vulnerability stems from improper memory handling within Safari's web content processing engine. When the browser encounters specially crafted malicious web content, the memory management routines fail to properly handle certain operations, leading to a crash condition. The vulnerability is classified under CWE-119, which encompasses issues where software performs operations on a memory buffer without properly restricting operations to within the intended boundaries.

The attack requires user interaction—specifically, a victim must navigate to or be redirected to a webpage containing the malicious content. The vulnerability affects the availability of the Safari browser and related WebKit components across Apple's ecosystem, though it does not appear to enable data exfiltration or unauthorized code execution based on current analysis.

Root Cause

The root cause lies in insufficient bounds checking or improper memory allocation during web content parsing operations. Safari's rendering engine, powered by WebKit, processes various types of web content including HTML, CSS, JavaScript, and media elements. When encountering malformed or specifically crafted content, the memory handling routines fail to properly validate or constrain operations, resulting in memory corruption that triggers a crash rather than being handled gracefully.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker would need to:

1. Craft malicious web content designed to trigger the memory handling flaw
2. Host the content on a controlled server or inject it into a legitimate website
3. Lure the victim to visit the malicious page through social engineering, phishing, or drive-by techniques

The vulnerability is exploited entirely through the network by delivering specially crafted content to the victim's browser. While the impact is limited to denial of service (crashing Safari), repeated exploitation could significantly disrupt a user's browsing experience and potentially be chained with other techniques.

Since this is a memory handling vulnerability exploited through malicious web content processing, the attack does not require authentication or elevated privileges from the attacker's perspective. See the Full Disclosure Security Post for additional technical context on this vulnerability class.

Detection Methods for CVE-2025-31257

Indicators of Compromise

• Repeated unexpected Safari crashes when visiting specific websites or loading particular content
• Browser crash reports indicating memory-related exceptions in WebKit processes
• WebContent process terminations logged in system diagnostics
• User reports of Safari becoming unresponsive before crashing during normal browsing

Detection Strategies

• Monitor endpoint telemetry for unusual patterns of Safari or WebContent process crashes
• Implement web filtering to block access to known malicious domains serving exploit content
• Deploy SentinelOne agents to detect anomalous browser process behavior and memory access patterns
• Correlate browser crash logs across the organization to identify potential targeted attacks

Monitoring Recommendations

• Enable crash reporting and centralize Safari crash logs for analysis
• Monitor network traffic for connections to suspicious domains known to host exploit kits
• Track WebKit-related process terminations through endpoint detection and response (EDR) solutions
• Establish baselines for normal browser crash rates to detect anomalies

How to Mitigate CVE-2025-31257

Immediate Actions Required

• Update Safari to version 18.5 or later immediately across all managed devices
• Update iOS and iPadOS devices to version 18.5 or later
• Update macOS Sequoia to version 15.5 or later
• Update watchOS to version 11.5, tvOS to version 18.5, and visionOS to version 2.5 as applicable
• Ensure automatic updates are enabled across the Apple device fleet

Patch Information

Apple has addressed this vulnerability with improved memory handling in the following releases:

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

Linux distributions using WebKitGTK should also apply relevant patches; see the Debian LTS Announcement for guidance.

Workarounds

• Use an alternative browser temporarily if patches cannot be immediately applied
• Exercise caution when clicking links from untrusted sources or unknown senders
• Deploy web content filtering to block access to suspicious or unverified websites
• Consider using Safari's Reader Mode where available to reduce exposure to complex web content

# 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