What is the CVSS score of CVE-2025-43526?

CVE-2025-43526 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

Which versions of macOS are affected by CVE-2025-43526?

CVE-2025-43526 is a critical vulnerability in Apple Safari and macOS Lockdown Mode that allows remote attackers to bypass security restrictions and access APIs that should be unavailable in…

How to fix or mitigate CVE-2025-43526?

Within 24 hours: Identify all users with Safari 26.2 or macOS Tahoe 26.2 with Lockdown Mode enabled, particularly high-risk users (executives, journalists, human rights defenders). Within 7 days: Deploy compensating controls by disabling Lockdown Mode only for users with alternative endpoint protection, or restrict Safari usage on vulnerable systems until patched; communicate patch timeline to affected users. Within 30 days: Apply vendor patch immediately upon Apple release; verify all identified systems are updated to patched version before re-enabling Lockdown Mode.

macOS CVE-2025-43526

CRITICAL

URL Redirection to Untrusted Site (Open Redirect) (CWE-601)

2025-12-17 product-security@apple.com

Authentication Bypass Apple macOS Safari

9.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Apr 02, 2026 - 19:37 vuln.today

CVE Published

Dec 17, 2025 - 21:16 nvd

CRITICAL 9.8

DescriptionCVE.org

This issue was addressed with improved URL validation. This issue is fixed in Safari 26.2, macOS Tahoe 26.2. On a Mac with Lockdown Mode enabled, web content opened via a file URL may be able to use Web APIs that should be restricted.

AnalysisAI

Apple Safari and macOS Lockdown Mode can be bypassed to access restricted Web APIs through maliciously crafted file URLs due to insufficient URL validation. Affects Safari 26.2 and macOS Tahoe 26.2 on systems with Lockdown Mode enabled. Remote attackers can potentially execute high-impact attacks leveraging APIs meant to be restricted in high-security configurations. EPSS score of 0.06% (18th percentile) indicates low observed exploitation probability. No public exploit identified at time of analysis. This represents a serious compromise of Apple's enhanced security feature designed to protect high-risk users from targeted attacks.

Technical ContextAI

Apple's Lockdown Mode is an optional security feature introduced to protect users facing targeted digital threats by restricting certain Web APIs and advanced browser features. This vulnerability stems from inadequate URL validation (CWE-601: URL Redirection to Untrusted Site) in how Safari and macOS handle file:// protocol URLs when Lockdown Mode is active. The flaw allows file-based web content to bypass the restricted API enforcement mechanism, effectively neutralizing protections intended to limit attack surface against sophisticated adversaries. The affected products are Apple Safari browser (all versions prior to 26.2) and macOS operating system (versions prior to Tahoe 26.2). The vulnerability specifically undermines the trust boundary that should exist between local file content and web-origin-based security policies, allowing file URLs to access capabilities that Lockdown Mode explicitly aims to disable for threat mitigation.

RemediationAI

Vendor-released patches are available and users should immediately update to Safari 26.2 and macOS Tahoe 26.2 (macOS 26.2), which address this issue through improved URL validation mechanisms. Organizations and individuals using Lockdown Mode should prioritize these updates as the feature's security guarantees are compromised in unpatched versions. Update Safari through the App Store or System Preferences Software Update mechanism, and update macOS through System Preferences/System Settings Software Update. Detailed installation guidance is provided in Apple's security advisories at https://support.apple.com/en-us/125886 (Safari) and https://support.apple.com/en-us/125892 (macOS). No effective workaround exists aside from disabling Lockdown Mode entirely, which would eliminate the intended security protections for high-risk users. Users should avoid opening untrusted file URLs or downloading files from unknown sources until systems are patched, particularly when Lockdown Mode is enabled.