CVE-2025-43433: Apple Safari Buffer Overflow Vulnerability

CVE-2025-43433 Overview

CVE-2025-43433 is a memory corruption vulnerability affecting Apple's WebKit browser engine across multiple Apple products. The vulnerability stems from improper memory handling when processing maliciously crafted web content, which could allow attackers to corrupt memory and potentially achieve arbitrary code execution on affected devices.

Critical Impact

Processing maliciously crafted web content may lead to memory corruption, potentially enabling attackers to execute arbitrary code or cause system instability across iOS, iPadOS, macOS, tvOS, visionOS, watchOS, and Safari.

Affected Products

• Apple Safari versions prior to 26.1
• Apple iOS 18.7.2 and iPadOS 18.7.2 and earlier
• Apple iOS 26.1 and iPadOS 26.1 and earlier
• Apple macOS Tahoe versions prior to 26.1
• Apple tvOS versions prior to 26.1
• Apple visionOS versions prior to 26.1
• Apple watchOS versions prior to 26.1

Discovery Timeline

• 2025-11-04 - CVE-2025-43433 published to NVD
• 2026-04-02 - Last updated in NVD database

Technical Details for CVE-2025-43433

Vulnerability Analysis

This vulnerability is classified under CWE-787 (Out-of-Bounds Write) and CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw exists within WebKit's memory handling routines, which fail to properly validate or constrain memory operations when parsing and rendering certain types of web content.

When a user visits a malicious webpage or loads untrusted web content, the improper memory handling can result in out-of-bounds memory writes. This type of vulnerability is particularly dangerous as it can be exploited remotely through the browser without requiring any special privileges, needing only that the user interact with malicious content.

The broad impact across Apple's ecosystem—spanning mobile devices, desktop systems, wearables, and AR/VR platforms—significantly increases the attack surface, as all these products share the vulnerable WebKit component.

Root Cause

The root cause is improper memory handling within WebKit's content processing routines. Specifically, the vulnerability involves insufficient bounds checking or improper memory allocation/deallocation when processing specially crafted web content. This allows attackers to write data outside the intended memory boundaries (CWE-787) or perform operations that exceed the allocated buffer limits (CWE-119).

Attack Vector

The attack requires network access and user interaction. An attacker can exploit this vulnerability by:

1. Hosting malicious web content on an attacker-controlled server or compromising a legitimate website
2. Tricking a victim into visiting the malicious page through phishing, malvertising, or social engineering
3. When the victim's browser processes the crafted content, the memory corruption occurs
4. Successful exploitation could lead to arbitrary code execution in the context of the browser process

The vulnerability is exploitable through any application that utilizes WebKit for rendering web content, including Safari, third-party browsers on iOS, and embedded web views within applications.

Detection Methods for CVE-2025-43433

Indicators of Compromise

• Unexpected browser crashes or instability when accessing web content
• Unusual memory consumption patterns in Safari or WebKit-based processes
• Anomalous network connections initiated by browser processes
• Unexpected child processes spawned by Safari or WebKit components

Detection Strategies

• Monitor for WebKit process crashes accompanied by memory access violations
• Implement endpoint detection rules for unusual behavior following web browsing activity
• Analyze memory dumps for signs of heap or buffer corruption patterns
• Deploy network-based detection for known malicious web content patterns

Monitoring Recommendations

• Enable crash reporting and analyze WebKit-related crash logs for exploitation attempts
• Monitor application behavior post-browsing for signs of compromise
• Implement content security policies to restrict execution of untrusted scripts
• Review browser process activity for unusual system calls or privilege escalation attempts

How to Mitigate CVE-2025-43433

Immediate Actions Required

• Update all Apple devices to the latest patched versions immediately
• Ensure automatic updates are enabled across your Apple device fleet
• Advise users to avoid visiting untrusted websites until patches are applied
• Consider implementing web content filtering to block known malicious domains

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. The following versions contain the fix:

• Safari 26.1
• iOS 18.7.2 and iPadOS 18.7.2
• iOS 26.1 and iPadOS 26.1
• macOS Tahoe 26.1
• tvOS 26.1
• visionOS 26.1
• watchOS 26.1

For detailed patch information, refer to the official Apple security advisories:

• Apple Security Advisory #125632
• Apple Security Advisory #125633
• Apple Security Advisory #125634
• Apple Security Advisory #125637
• Apple Security Advisory #125638
• Apple Security Advisory #125639
• Apple Security Advisory #125640

Workarounds

• Enable JavaScript blocking or use content blockers to reduce attack surface temporarily
• Restrict access to untrusted or unknown websites until patching is complete
• Use a non-WebKit browser on macOS if immediate patching is not possible
• Implement network-level content filtering to block potentially malicious web content
• Consider isolating unpatched devices from sensitive network segments

# 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