CVE-2025-43458: Apple Safari DOS Vulnerability

CVE-2025-43458 Overview

CVE-2025-43458 is an input validation flaw [CWE-20] in Apple's WebKit-based browser engine affecting Safari and multiple Apple operating systems. Processing maliciously crafted web content can trigger an unexpected process crash, causing a denial-of-service condition in the browser or WebView-hosting application. Apple resolved the issue through improved state management in Safari 26.1, iOS 18.7.2, iPadOS 18.7.2, iOS 26.1, iPadOS 26.1, macOS Tahoe 26.1, tvOS 26.1, visionOS 26.1, and watchOS 26.1. The vulnerability requires user interaction, such as visiting an attacker-controlled webpage, and does not affect confidentiality or integrity.

Critical Impact
Remote attackers can crash the WebKit rendering process by luring users to malicious web content, resulting in browser or app instability across Apple's ecosystem.

Affected Products

Apple Safari (prior to 26.1)
Apple iOS and iPadOS (prior to 18.7.2 and 26.1)
Apple macOS Tahoe, tvOS, visionOS, and watchOS (prior to 26.1)

Discovery Timeline

2025-11-04 - CVE-2025-43458 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-43458

Vulnerability Analysis

CVE-2025-43458 originates in WebKit, the browser engine that powers Safari and any application rendering web content on Apple platforms. Apple describes the defect as a state management issue triggered when the engine processes maliciously crafted web content. When the affected state transitions occur in an unexpected order, WebKit enters an invalid execution path and terminates the content process.

Because WebKit is embedded in system frameworks such as WKWebView, the impact extends beyond Safari to third-party applications that load remote content. Successful exploitation degrades availability by crashing the tab or host process. Confidentiality and integrity remain unaffected, and no arbitrary code execution has been reported.

Root Cause

The root cause is improper input validation [CWE-20] combined with insufficient state tracking during content processing. WebKit fails to guarantee that internal objects remain in a consistent state when handling attacker-controlled input, causing an abort or fatal exception. Apple's fix hardens the state machine to reject or safely handle the malformed sequences.

Attack Vector

An attacker hosts a webpage containing the malicious payload and convinces a user to visit it. The delivery channel can be a phishing link, a compromised site, or a malvertising campaign. When the target's browser or WebView parses the content, the WebKit process crashes. No authentication is required, and the vulnerability is exploitable across the network.

No public proof-of-concept, exploit code, or CISA KEV listing exists for CVE-2025-43458 at publication time. The EPSS probability is 0.562% (42.7 percentile).

Detection Methods for CVE-2025-43458

Indicators of Compromise

Repeated com.apple.WebKit.WebContent or Safari renderer process crashes recorded in ~/Library/Logs/DiagnosticReports/ on macOS or in device crash logs on iOS/iPadOS.
Application crash telemetry showing WebKit content process terminations shortly after loading external URLs.
Endpoint logs correlating browser crash events with visits to newly registered or low-reputation domains.

Detection Strategies

Monitor operating system crash reporters for spikes in WebKit content-process aborts across managed Apple devices.
Correlate DNS and proxy logs with browser crash timestamps to identify user visits to suspicious pages preceding failures.
Track Safari and third-party WebView application versions through mobile device management (MDM) inventory to flag hosts running unpatched builds.

Monitoring Recommendations

Enable MDM-based software inventory reporting for Safari, iOS, iPadOS, macOS, tvOS, visionOS, and watchOS versions.
Ingest Apple unified logs and crash reports into a centralized SIEM for anomaly detection on WebKit subsystems.
Alert on outbound traffic to domains flagged by threat intelligence feeds when accompanied by browser process termination events.

How to Mitigate CVE-2025-43458

Immediate Actions Required

Upgrade to Safari 26.1, iOS 18.7.2 or 26.1, iPadOS 18.7.2 or 26.1, macOS Tahoe 26.1, tvOS 26.1, visionOS 26.1, and watchOS 26.1 as soon as feasible.
Push updates to managed fleets through MDM policies and enforce compliance for devices that access sensitive resources.
Advise users to avoid clicking links from untrusted sources until patches are deployed.

Patch Information

Apple published fixes in the advisories listed under Apple Support articles HT125632, HT125633, HT125634, HT125637, HT125638, HT125639, and HT125640. Each advisory documents the affected platform and confirms the state management improvement in WebKit.

Workarounds

Restrict browsing to trusted sites and disable JavaScript on untrusted origins using Safari content settings where practical.
Deploy DNS filtering or secure web gateway policies to block known malicious domains delivering exploit content.
Configure MDM restrictions to prevent installation of third-party applications embedding outdated WebViews on managed devices.

bash

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

# Trigger a software update check on macOS
sudo softwareupdate --list
sudo softwareupdate --install --all --restart