CVE-2025-43438: Apple Safari Use-After-Free Vulnerability

CVE-2025-43438 Overview

CVE-2025-43438 is a use-after-free vulnerability [CWE-416] in Apple's WebKit-based Safari browser and related operating systems. Processing maliciously crafted web content may trigger an unexpected Safari crash. Apple addressed the flaw with improved memory management across Safari 26.1, iOS/iPadOS 18.7.2, iOS/iPadOS 26.1, macOS Tahoe 26.1, visionOS 26.1, and watchOS 26.1.

The vulnerability requires user interaction, as a victim must visit a malicious webpage or open crafted content in Safari. Impact is limited to availability, resulting in a browser crash rather than code execution or data disclosure.

Critical Impact
Processing maliciously crafted web content can cause Safari to crash, disrupting browsing sessions across Apple's mobile, desktop, wearable, and spatial computing platforms.

Affected Products

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

Discovery Timeline

2025-11-04 - CVE-2025-43438 published to NVD
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2025-43438

Vulnerability Analysis

CVE-2025-43438 is a use-after-free condition in Apple's web content processing stack, which underpins Safari and the WebKit component shared across Apple operating systems. Use-after-free bugs occur when a program continues to reference memory after it has been freed, allowing the freed allocation to be reused for a different object. When the stale pointer is dereferenced, the process operates on unexpected data and typically crashes.

Exploitation requires a user to load maliciously crafted web content. The reported impact is limited to a Safari crash, which maps to a denial-of-service outcome for the affected tab or process. Apple's advisory does not indicate that the flaw enables arbitrary code execution or data exfiltration.

The EPSS probability is 1.054% (60th percentile), indicating a low predicted likelihood of exploitation within the next 30 days. No public proof-of-concept, exploit code, or in-the-wild activity has been reported, and the CVE is not listed in the CISA Known Exploited Vulnerabilities catalog.

Root Cause

The root cause is improper object lifetime management within WebKit's web content handling. A code path releases an object while a reference remains reachable, and subsequent access to the freed memory triggers undefined behavior. Apple's fix hardens memory management around the affected object to prevent the dangling reference.

Attack Vector

An attacker hosts crafted HTML, JavaScript, or related web content on an attacker-controlled site or delivers it through a compromised page, malvertising, or a phishing link. When the victim opens the content in Safari or any WebKit-based view on an affected Apple platform, the parser reaches the vulnerable code path and crashes the browser process.

The vulnerability manifests during rendering of malicious web content. No verified proof-of-concept code is available. See the Red Hat CVE Analysis CVE-2025-43438 and Apple Support Article 125632 for advisory details.

Detection Methods for CVE-2025-43438

Indicators of Compromise

Repeated Safari or WebKit process crashes (com.apple.WebKit.WebContent) recorded in device crash logs after visiting a specific URL.
Diagnostic reports referencing EXC_BAD_ACCESS or memory-access faults in WebKit rendering threads.
Outbound connections from Safari to previously unseen domains immediately preceding a browser crash event.

Detection Strategies

Collect and parse macOS and iOS crash reports (~/Library/Logs/DiagnosticReports/) for recurring Safari or WebContent process terminations tied to WebKit stack frames.
Correlate browser telemetry with proxy and DNS logs to identify users repeatedly loading URLs that precede Safari crashes.
Alert on Apple endpoints running Safari, iOS, iPadOS, macOS, visionOS, or watchOS versions below the fixed releases identified in Apple's advisories.

Monitoring Recommendations

Track patch compliance for Safari 26.1, iOS/iPadOS 18.7.2 and 26.1, macOS Tahoe 26.1, visionOS 26.1, and watchOS 26.1 across managed fleets via MDM reporting.
Monitor web proxy logs for content flagged by threat intelligence feeds targeting WebKit clients.
Review Red Hat advisories such as RHSA-2025:22789 and RHSA-2025:23110 for downstream WebKit package updates on Linux systems.

How to Mitigate CVE-2025-43438

Immediate Actions Required

Update Safari to version 26.1 on macOS and upgrade Apple operating systems to iOS 18.7.2, iPadOS 18.7.2, iOS 26.1, iPadOS 26.1, macOS Tahoe 26.1, visionOS 26.1, or watchOS 26.1.
Deploy Red Hat WebKitGTK updates on affected Linux distributions using the referenced RHSA advisories.
Push updates through MDM to enforce minimum OS versions and block enrollment of non-compliant devices from sensitive resources.

Patch Information

Apple resolved CVE-2025-43438 by improving memory management in the affected WebKit code path. Fixed builds are documented in Apple Support Article 125632, Article 125633, Article 125634, Article 125638, Article 125639, and Article 125640. Red Hat published corresponding WebKitGTK updates across multiple advisories including RHSA-2025:23433 and RHSA-2025:23742.

Workarounds

Restrict browsing to trusted sites and block known-malicious domains at the network proxy or DNS resolver until patches are deployed.
Use content filtering and script-blocking browser extensions where supported to reduce exposure to untrusted JavaScript.
Encourage users to close and relaunch Safari after unexpected crashes and to report the originating URL to the security team.

bash

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

# Check iOS/iPadOS version compliance via MDM query or on-device
# Settings > General > About > Software Version (expect 18.7.2 or 26.1+)

# Red Hat / RHEL WebKitGTK update
sudo dnf update webkit2gtk4.0 webkit2gtk4.1