CVE-2026-43676: Apple Safari DOS Vulnerability

CVE-2026-43676 Overview

CVE-2026-43676 is an out-of-bounds access vulnerability in Apple's WebKit-based Safari browser and related operating systems. Processing maliciously crafted web content can trigger an unexpected Safari crash, resulting in denial of service on affected devices. Apple addressed the flaw through improved bounds checking in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2. The weakness is classified under CWE-125 (Out-of-Bounds Read) and requires user interaction, typically by visiting an attacker-controlled webpage.

Critical Impact
Remote attackers can crash Safari across iOS, iPadOS, macOS, and standalone Safari installations by serving crafted web content, affecting availability without requiring authentication.

Affected Products

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

Discovery Timeline

2026-06-29 - CVE-2026-43676 published to NVD
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2026-43676

Vulnerability Analysis

The flaw resides in Safari's web content processing pipeline, where an out-of-bounds access occurs when parsing or rendering specific maliciously crafted content. When Safari processes the malformed input, the affected component reads memory outside the allocated buffer boundary. The resulting memory access violation leads to an unexpected process crash.

The vulnerability affects confidentiality and integrity minimally but has a high impact on availability. Attackers exploit the flaw remotely across the network, and a victim must interact with the malicious content by visiting a webpage. The EPSS score is 0.257%, indicating limited observed exploitation activity in the wild at the time of publication.

Root Cause

The root cause is missing or insufficient bounds checking in a Safari content-handling routine. When crafted input drives the parser beyond expected boundaries, the code reads memory it should not access. Apple's patch introduces improved bounds validation to reject or safely handle out-of-range accesses before they occur.

Attack Vector

An attacker hosts crafted web content on a controlled or compromised server. A user visits the page using a vulnerable Safari version, triggering the out-of-bounds access during content processing. The Safari process crashes, disrupting the browsing session. Attack delivery vectors include phishing links, malicious advertisements, and compromised third-party content embedded in legitimate sites.

No public proof-of-concept exploit is available. See the Apple Support Document #127594 for vendor-provided technical context.

Detection Methods for CVE-2026-43676

Indicators of Compromise

Repeated unexpected Safari or WebKit process crashes on iOS, iPadOS, or macOS endpoints, particularly correlated with visits to unfamiliar domains.
Crash reports referencing WebKit content processes with out-of-bounds read signatures in operating system diagnostic logs.
Outbound network connections to newly registered or low-reputation domains immediately preceding Safari termination events.

Detection Strategies

Monitor endpoint telemetry for anomalous Safari or com.apple.WebKit.WebContent process termination events.
Correlate browser crash events with URL access history to identify potentially malicious pages.
Ingest macOS unified logs and iOS crash reports into a centralized analytics platform to identify patterns across the fleet.

Monitoring Recommendations

Track Safari version inventory across managed Apple devices to identify unpatched endpoints.
Alert on clusters of Safari crashes across multiple users visiting the same domain, which may indicate active exploitation attempts.
Review Mobile Device Management (MDM) compliance reports to verify iOS, iPadOS, and macOS update status.

How to Mitigate CVE-2026-43676

Immediate Actions Required

Update all Apple endpoints to Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2 or later.
Push updates through MDM to enforce timely patching across managed fleets.
Educate users to avoid clicking untrusted links until updates are applied.

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 the vendor advisories: Apple Support Document #127594, Apple Support Document #127595, and Apple Support Document #127685.

Workarounds

Restrict Safari usage to trusted domains via web content filtering or MDM-managed allowlists until patches are deployed.
Deploy network-layer filtering to block known malicious domains and reduce exposure to crafted web content.
Encourage use of alternative, up-to-date browsers on macOS where feasible until Safari is updated.

bash

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

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