CVE-2026-20660 is a vulnerability in Apple Safari caused by improper path handling logic, which allows a remote attacker to write arbitrary files on the victim's device. This vulnerability is classified under CWE-22, indicating that the software fails to properly restrict pathname inputs, enabling directory traversal or manipulation attacks. The flaw affects multiple Apple operating systems and Safari versions prior to the patched releases: macOS Tahoe 26.3, macOS Sonoma 14.8.4, iOS 18.7.5, iPadOS 18.7.5, visionOS 26.3, iOS 26.3, iPadOS 26.3, and Safari 26.3. Exploitation requires no privileges and no authentication but does require user interaction, such as visiting a malicious website or opening crafted content in Safari. The CVSS v3.1 score is 5.5 (medium severity), with the vector AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N, indicating local attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, no confidentiality or availability impact, but high impact on integrity due to arbitrary file writes. The vulnerability could allow attackers to place malicious files on the system, potentially leading to persistent compromise or further exploitation. Apple has addressed this issue with improved path handling logic in the specified updates. No public exploits or active exploitation have been reported to date.

The primary impact of CVE-2026-20660 is the unauthorized modification of system or user files through arbitrary file writes, which compromises the integrity of affected systems. Attackers could leverage this to implant persistent malware, modify configuration files, or disrupt application behavior. Although confidentiality and availability are not directly affected, the ability to write arbitrary files can facilitate further attacks such as privilege escalation or data tampering. Organizations relying on Apple devices and Safari browsers are at risk, especially if users interact with malicious web content. The requirement for user interaction limits the attack surface somewhat, but the lack of required privileges or authentication means any user can be targeted. This vulnerability could be particularly impactful in environments with sensitive data or critical infrastructure where integrity is paramount. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits post-disclosure.

To mitigate CVE-2026-20660, organizations should prioritize applying the official patches released by Apple for all affected platforms and Safari versions, including macOS Tahoe 26.3, macOS Sonoma 14.8.4, iOS 18.7.5, iPadOS 18.7.5, visionOS 26.3, iOS 26.3, iPadOS 26.3, and Safari 26.3. Beyond patching, organizations should implement strict web browsing policies to limit exposure to untrusted or malicious websites, including the use of web filtering and content security policies. User education is critical to reduce risky behaviors such as clicking unknown links or opening suspicious content. Employ endpoint protection solutions capable of detecting anomalous file writes or unauthorized modifications. Monitoring file system changes and leveraging application whitelisting can help detect or prevent exploitation attempts. Network segmentation and least privilege principles reduce the impact if a device is compromised. Regular vulnerability scanning and threat intelligence updates will help identify and respond to emerging exploit attempts related to this vulnerability.