CVE-2025-43402: 
macOS vulnerability analysis and mitigation

CVE-2025-43402 is a memory corruption vulnerability in the WindowServer component of Apple macOS that allows a local app to cause unexpected system termination or corrupt process memory. It was first disclosed by Apple on November 3, 2025, as part of the macOS Tahoe 26.1 release notes, and subsequently extended to cover macOS Sequoia 15.7.4 and macOS Sonoma 14.8.4 in a February 2026 update. The vulnerability was discovered and reported by @cloudlldb of @pixiepointsec. It carries a CVSS v3.1 base score of 7.8 (High) (Apple Advisory, Apple Sequoia, Apple Sonoma).

The root cause is classified as CWE-787 (Out-of-bounds Write), as assigned by CISA-ADP, with Apple describing the fix as "improved memory handling" in the WindowServer component — the macOS display server responsible for managing windows and graphical rendering. The attack vector is local (AV:L), requiring low privileges and no user interaction, meaning a sandboxed or unprivileged app running on the system could trigger the flaw. The precise mechanism (e.g., specific API call or data structure triggering the out-of-bounds write) has not been publicly detailed beyond Apple's advisory. No public proof-of-concept code has been identified at this time (Apple Advisory, Apple Sequoia).

Successful exploitation could allow a malicious application to cause unexpected system termination (denial of service) or corrupt process memory within the WindowServer context, potentially leading to privilege escalation or arbitrary code execution in a privileged process. Because WindowServer runs with elevated privileges and manages all graphical output on macOS, memory corruption in this component could have broad system-level consequences, including instability or unauthorized access to data rendered on screen. The vulnerability affects confidentiality, integrity, and availability — all rated High in the CVSS scoring (Apple Advisory, Apple Sonoma).

Apple has released patches addressing CVE-2025-43402 across three macOS versions: macOS Tahoe 26.1 (released November 3, 2025), macOS Sequoia 15.7.4 (released February 11, 2026), and macOS Sonoma 14.8.4 (released February 11, 2026). Users should update to one of these patched versions via System Settings > Software Update. No configuration-based workarounds have been published by Apple; upgrading is the only recommended remediation (Apple Advisory, Apple Sequoia, Apple Sonoma).

The vulnerability was credited to @cloudlldb of @pixiepointsec, who also received additional recognition in the WindowServer section of the macOS Tahoe, Sequoia, and Sonoma advisories. No notable public commentary, blog posts, or media coverage specific to this CVE has been identified beyond the standard Apple security advisory disclosures (Apple Advisory).