CVE-2025-43521: 
macOS vulnerability analysis and mitigation

CVE-2025-43521 is a downgrade vulnerability in the AppleMobileFileIntegrity component affecting Intel-based Mac computers, where insufficient code-signing restrictions allow a malicious app to access sensitive user data. The vulnerability was disclosed on December 12, 2025, when Apple released macOS Sequoia 15.7.3, and was subsequently also addressed in macOS Tahoe 26.2. It was reported by an anonymous researcher. The CVSS v3.1 base score is 5.5 (Medium), reflecting a local attack vector requiring user interaction with high confidentiality impact (Apple Advisory 15.7.3, Apple Advisory Tahoe 26.2).

The root cause is classified as CWE-347 (Improper Verification of Cryptographic Signature), manifesting as a downgrade issue in the AppleMobileFileIntegrity subsystem on Intel-based Macs. An attacker can craft or deliver an application that exploits insufficient code-signing enforcement to downgrade security checks, bypassing protections that would normally prevent unauthorized access to sensitive user data. Exploitation requires local access and some degree of user interaction (e.g., running a malicious app), and is limited to Intel-based Mac hardware. Apple addressed the issue by adding additional code-signing restrictions (Apple Advisory 15.7.3, Apple Advisory Tahoe 26.2).

Successful exploitation allows a malicious application to access sensitive user data that would otherwise be protected by macOS integrity mechanisms. The impact is limited to confidentiality — there is no integrity or availability impact. The vulnerability is scoped to Intel-based Mac systems and does not enable remote code execution or privilege escalation on its own, but could be chained with other vulnerabilities to facilitate broader data exfiltration (Apple Advisory 15.7.3).

Apple has released patches addressing CVE-2025-43521 in macOS Sequoia 15.7.3 (released December 12, 2025) and macOS Tahoe 26.2. Users running Intel-based Macs should update to macOS Sequoia 15.7.3 or later immediately. No configuration-based workarounds have been published; upgrading to a patched macOS version is the only recommended remediation (Apple Advisory 15.7.3, Apple Advisory Tahoe 26.2).

The CIS (Center for Internet Security) issued an advisory noting multiple vulnerabilities in Apple products patched in this release cycle, including CVE-2025-43521, recommending prompt updates (CIS Advisory). The vulnerability received standard coverage in security community channels, with no notable controversy or significant researcher commentary beyond routine patch tracking.