CVE-2025-43209: Apple iPadOS Buffer Overflow Vulnerability

CVE-2025-43209 Overview

CVE-2025-43209 is an out-of-bounds write vulnerability (CWE-787) affecting multiple Apple operating systems including macOS, iOS, iPadOS, tvOS, watchOS, and visionOS. The vulnerability exists in the web content processing components and can be triggered when Safari or WebKit-based applications process maliciously crafted web content. Successful exploitation leads to an unexpected Safari crash, potentially enabling denial of service conditions.

This vulnerability has been addressed by Apple through improved bounds checking in their security updates released in July 2025. The flaw affects a wide range of Apple devices and platforms, making it a significant concern for enterprise environments with Apple device deployments.

Critical Impact

Processing maliciously crafted web content may lead to an unexpected Safari crash. The network-accessible attack vector with no authentication requirements makes this vulnerability exploitable through malicious websites or web-based attacks.

Affected Products

• Apple macOS Sequoia (versions prior to 15.6)
• Apple macOS Sonoma (versions prior to 14.7.7)
• Apple macOS Ventura (versions prior to 13.7.7)
• Apple iOS (versions prior to 18.6)
• Apple iPadOS (versions prior to 18.6 and 17.7.9)
• Apple tvOS (versions prior to 18.6)
• Apple watchOS (versions prior to 11.6)
• Apple visionOS (versions prior to 2.6)

Discovery Timeline

• July 30, 2025 - CVE-2025-43209 published to NVD
• November 3, 2025 - Last updated in NVD database

Technical Details for CVE-2025-43209

Vulnerability Analysis

The vulnerability stems from improper bounds checking in Apple's web content processing engine. When parsing maliciously crafted web content, the affected component fails to properly validate array or buffer boundaries before performing write operations. This results in an out-of-bounds write condition (CWE-787) where data is written beyond the allocated memory region.

Out-of-bounds write vulnerabilities are particularly dangerous as they can corrupt adjacent memory structures, potentially leading to code execution, privilege escalation, or denial of service. In this case, Apple has confirmed the immediate impact is an unexpected Safari crash, indicating a denial of service condition.

The vulnerability can be exploited remotely over the network without requiring any user authentication or special privileges. An attacker could craft a malicious webpage containing specially formatted content that, when processed by Safari or any WebKit-based browser, triggers the out-of-bounds write condition.

Root Cause

The root cause of CVE-2025-43209 is insufficient bounds checking in the web content processing code. When handling certain web content structures, the code fails to verify that write operations remain within allocated buffer boundaries. Apple addressed this by implementing improved bounds checking to ensure all memory access operations are properly validated against buffer limits.

This type of vulnerability typically occurs when:

• Array indices are not validated before use
• Calculated offsets exceed buffer boundaries
• Loop conditions fail to properly constrain iteration limits
• Type confusion leads to incorrect size calculations

Attack Vector

The attack vector for this vulnerability is network-based. An attacker can exploit this vulnerability by:

1. Hosting maliciously crafted web content on a controlled server
2. Luring victims to visit the malicious webpage through phishing, social engineering, or compromised legitimate websites
3. The victim's browser processes the malicious content, triggering the out-of-bounds write
4. Safari crashes unexpectedly, causing denial of service

The attack requires no authentication and no user interaction beyond visiting the malicious page. The vulnerability affects all WebKit-based browsers and applications on the affected Apple platforms.

Since no verified code examples are available for this vulnerability, technical details should be referenced from the Apple Security Support Documents and the Full Disclosure mailing list posts for additional context on the exploitation mechanism.

Detection Methods for CVE-2025-43209

Indicators of Compromise

• Unexpected Safari or WebKit-based application crashes when browsing web content
• Crash logs showing memory corruption or out-of-bounds access in WebKit components
• ReportCrash entries indicating crashes in com.apple.WebKit.WebContent or related processes
• Network traffic to suspicious or newly registered domains serving web content

Detection Strategies

• Monitor system crash reports for Safari and WebKit-related process crashes
• Implement network-based detection for malicious web content patterns associated with this CVE
• Deploy endpoint detection solutions capable of identifying WebKit exploitation attempts
• Review browser process crash frequency across managed Apple devices for anomalies

Monitoring Recommendations

• Enable crash report collection and analysis for Safari and WebKit processes on managed devices
• Monitor MDM solutions for unusual Safari crash patterns across the device fleet
• Implement web filtering to block access to known malicious domains
• Configure SentinelOne agents to monitor for WebKit process anomalies and memory corruption indicators

How to Mitigate CVE-2025-43209

Immediate Actions Required

• Update all Apple devices to the latest patched versions immediately
• Prioritize patching for devices with internet-facing browser access
• Consider temporarily restricting web browsing to trusted sites on unpatched devices
• Enable automatic updates to ensure timely application of future security patches

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. Organizations should update to the following versions or later:

For detailed patch information, refer to:

• Apple Security Support Document #124147
• Apple Security Support Document #124148
• Apple Security Support Document #124149
• Apple Security Support Document #124150
• Apple Security Support Document #124151
• Apple Security Support Document #124153
• Apple Security Support Document #124154
• Apple Security Support Document #124155

Workarounds

• Use alternative browsers not based on WebKit until patches can be applied (note: iOS requires WebKit for all browsers)
• Implement network-level web content filtering to block known malicious content
• Restrict web browsing to vetted, trusted websites on critical systems
• Consider disabling JavaScript in Safari settings as a temporary measure (may impact website functionality)

# Check current macOS version
sw_vers

# Check for available updates on macOS
softwareupdate --list

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

# For iOS/iPadOS, update via Settings > General > Software Update
# Or use Apple Configurator 2 or MDM solutions for managed devices