CVE-2026-43725: Apple Safari XSS Vulnerability

CVE-2026-43725 Overview

CVE-2026-43725 is an input validation vulnerability affecting Apple Safari, iOS, iPadOS, and macOS Tahoe. A malicious website can process restricted web content outside the WebKit sandbox, undermining a core browser security boundary. Apple addressed the flaw with improved input validation in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2. The weakness maps to [CWE-20] Improper Input Validation. Exploitation requires user interaction, typically visiting an attacker-controlled page, and can result in loss of confidentiality, integrity, and availability across a security scope change.

Critical Impact
A crafted website can escape WebKit sandbox restrictions and process restricted web content in a more privileged context on unpatched Apple devices.

Affected Products

Apple Safari (prior to 26.5.2)
Apple iOS and iPadOS (prior to 26.5.2)
Apple macOS Tahoe (prior to 26.5.2)

Discovery Timeline

2026-06-29 - CVE-2026-43725 published to NVD
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2026-43725

Vulnerability Analysis

The flaw resides in how Safari and WebKit validate input associated with web content processing. Insufficient checks allow a malicious page to route restricted content along a path that operates outside the browser sandbox. WebKit's sandbox is designed to isolate untrusted web content from the underlying operating system and other browsing contexts. Bypassing that boundary lets attacker-controlled content interact with resources that should remain unreachable from a rendered page. The advisory notes a security scope change, indicating that exploitation impacts components beyond the vulnerable process itself. Confidentiality, integrity, and availability impacts are each rated low, consistent with partial rather than full compromise. Exploitation requires the victim to load or interact with an attacker-controlled site, and no privileges on the target device are needed. Apple has not disclosed the specific WebKit subsystem affected, and no public exploit or in-the-wild activity has been reported.

Root Cause

The root cause is improper input validation [CWE-20] in a WebKit code path that handles restricted web content. Missing or inadequate checks let content bypass sandbox routing and reach a component where sandbox constraints are not enforced.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker hosts a crafted page and lures a victim to visit it, for example through phishing, malvertising, or a compromised site. When the browser processes the page, the validation gap enables restricted content handling outside the sandbox.

No verified public exploit code is available for CVE-2026-43725. See the Apple Support Document #127594, Apple Support Document #127595, and Apple Support Document #127685 for vendor details.

Detection Methods for CVE-2026-43725

Indicators of Compromise

Safari or WebKit-based application processes spawning unexpected child processes or accessing files outside typical browser sandbox paths.
Outbound connections from browser processes to newly registered or low-reputation domains immediately after page loads.
Crash logs referencing WebKit content process termination followed by anomalous process activity on macOS or iOS management telemetry.

Detection Strategies

Inventory Safari, iOS, iPadOS, and macOS versions across managed devices and flag any build below 26.5.2.
Correlate web proxy or DNS logs with endpoint telemetry to identify users visiting suspicious sites followed by unusual browser child-process behavior.
Hunt for WebKit content process anomalies, such as unexpected IPC to system services or attempts to access user data outside origin scope.

Monitoring Recommendations

Enable mobile device management (MDM) compliance rules that require the patched OS builds and quarantine noncompliant devices.
Monitor Apple security advisory feeds and integrate them into vulnerability management workflows for rapid triage.
Track EPSS movement for CVE-2026-43725 (currently 0.314%) alongside threat intelligence signals for emerging exploitation.

How to Mitigate CVE-2026-43725

Immediate Actions Required

Update Safari to 26.5.2 on all supported macOS systems.
Update iPhone and iPad devices to iOS 26.5.2 or iPadOS 26.5.2.
Update macOS Tahoe systems to build 26.5.2.
Prioritize patching of devices used for high-risk browsing, executive access, or handling sensitive data.

Patch Information

Apple released fixes in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2. Refer to Apple Support Document #127594, Apple Support Document #127595, and Apple Support Document #127685 for full advisory content and download instructions.

Workarounds

Restrict use of Safari on unpatched devices and route browsing through hardened alternatives where feasible until updates are applied.
Enforce web content filtering to block known malicious and low-reputation domains at the network edge.
Educate users to avoid clicking unsolicited links and to report suspicious pages that trigger browser instability.

bash

# Verify Safari version on macOS
mdls -name kMDItemVersion /Applications/Safari.app

# Trigger software update check on macOS
sudo softwareupdate -l
sudo softwareupdate -i -a -R