CVE-2026-43699: Apple Safari and iOS Use-After-Free Vulnerability – CVSS 6.5

Technical summary

CVE-2026-43699 is a use-after-free vulnerability (CWE-416) in Apple's WebKit rendering engine and related system components. Use-after-free occurs when software attempts to access memory that has already been freed, leading to undefined behavior. In this case, processing crafted web content triggers a code path that references deallocated memory, resulting in an unexpected process termination. The vulnerability has a CVSS 3.1 score of 6.5 (Medium) with a vector indicating network-based attack, low complexity, no privilege requirement, user interaction needed, and high availability impact with no confidentiality or integrity compromise.

Business impact

Organizations relying on Apple devices for employee productivity face potential workflow disruption if users encounter malicious websites triggering browser crashes. Remote attackers could cause repeated denial-of-service conditions against individual users, though the impact is limited to process crashes rather than data exfiltration or code execution. For consumer-facing services, this could affect user experience and support costs. The medium severity reduces enterprise-wide risk, but concentrated attacks on specific user groups could degrade productivity.

Affected systems

Safari browser on macOS, iOS and iPadOS, tvOS, visionOS, and watchOS all contain this vulnerability. Specific fixed versions are Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, macOS Tahoe 26.5.2, tvOS 26.6, visionOS 26.6, and watchOS 26.6. Versions prior to these releases are vulnerable. The vulnerability affects a broad range of Apple platforms but is most operationally relevant to iOS/iPadOS devices and desktop Mac systems.

Exploitability

Exploitation requires user interaction: an attacker must trick or socially engineer a user into visiting a malicious website. There is no remote code execution, privilege escalation, or persistent compromise; the sole impact is process crash. No known public exploits or active campaigns leveraging this vulnerability have been tracked in the KEV catalog. The barrier to exploitation is low once a victim visits a crafted page, but the impact scope is narrow—denial of service only.

Remediation

Users and administrators must update affected devices to the patched versions specified: Safari 26.5.2 (and corresponding OS versions), tvOS 26.6, visionOS 26.6, and watchOS 26.6. Enable automatic updates where possible to ensure timely patching. Organizations with managed iOS/iPadOS/macOS deployments should prioritize rolling out patches through mobile device management or software update mechanisms. Interim risk reduction: educate users to avoid suspicious links and enable browser security features.

Patch guidance

Apply the following patches: Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, macOS Tahoe 26.5.2, tvOS 26.6, visionOS 26.6, and watchOS 26.6. For macOS, use System Settings > General > Software Update. For iOS/iPadOS, use Settings > General > Software Update. For watchOS and tvOS, use the respective device settings or companion apps. Verify patched versions are installed by checking About settings on each device. Organizations should schedule updates during maintenance windows to avoid user disruption, though the patches are generally safe to deploy broadly given the medium severity.

Detection guidance

Monitor for unexpected Safari or system process crashes in device logs and error reporting dashboards. On macOS and iOS, enable crash reporting through System Preferences or iCloud settings to capture use-after-free signatures. Intrusion detection systems cannot meaningfully detect exploitation since it manifests as a local process crash; focus on detection of malicious web content distribution via DNS or network filtering. Endpoint detection and response (EDR) tools should flag repeated process crashes from Safari on the same device as a potential indicator of exploitation attempts.

Why prioritize this

This is a Medium-severity denial-of-service vulnerability affecting widely deployed Apple platforms. While it lacks the severity of remote code execution flaws, the ease of exploitation (malicious website visit) and broad device coverage make it a reasonable patching priority within normal update cycles. Organizations should address this in standard patch management schedules rather than emergency windows. Resources should be reserved for critical vulnerabilities with integrity or confidentiality impact.

Risk score, explained

The CVSS 3.1 score of 6.5 reflects the combination of network attack vector and low complexity balanced against the lack of confidentiality or integrity impact. The user interaction requirement and process-crash-only outcome lower the score compared to remote code execution flaws. For most enterprises, this represents elevated but manageable risk—notable enough to patch within quarterly cycles but not an emergency.

Frequently asked questions