CVE-2026-20648 is a privacy vulnerability identified in Apple macOS, specifically affecting the handling of notifications synchronized across iCloud devices. The root cause is that sensitive notification data was stored in a location accessible by malicious applications, allowing them to read notifications originating from other devices linked to the same iCloud account. This exposure violates user privacy by potentially leaking sensitive information contained in notifications. The vulnerability was addressed by Apple in macOS Tahoe 26.3 by moving this sensitive data to a protected location, thereby restricting unauthorized access. The CVSS v3.1 base score is 5.5 (medium severity), with an attack vector of local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), unchanged scope (S:U), high impact on confidentiality (C:H), and no impact on integrity or availability (I:N/A:N). Exploitation requires a malicious app to be installed on the victim’s macOS device and user interaction to trigger the access. There are no known exploits in the wild at this time. The vulnerability is classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). This issue highlights the risks associated with inter-device data synchronization and the importance of secure data storage practices within operating systems. Organizations relying on macOS devices with iCloud integration should be aware of this risk and apply the available patch promptly to safeguard user privacy.

The primary impact of CVE-2026-20648 is the unauthorized disclosure of sensitive notification content from other iCloud devices, which can lead to privacy violations and potential leakage of confidential information such as personal messages, authentication codes, or sensitive alerts. Although the vulnerability does not affect data integrity or system availability, the confidentiality breach can have significant consequences, including social engineering attacks, identity theft, or exposure of sensitive business communications. For organizations, especially those with employees using macOS devices linked to iCloud, this vulnerability could lead to data leakage across corporate and personal boundaries. The requirement for local access and user interaction limits remote exploitation but does not eliminate risk from insider threats or malware that can trick users into interaction. The absence of known exploits reduces immediate risk but does not preclude future exploitation attempts. Overall, the vulnerability poses a moderate risk to privacy and data confidentiality in environments where macOS devices are prevalent.

To mitigate CVE-2026-20648, organizations and users should: 1) Immediately update all affected macOS devices to version Tahoe 26.3 or later, where the vulnerability is fixed by relocating sensitive notification data to a protected location. 2) Restrict installation of untrusted or unsigned applications to reduce the risk of malicious apps gaining local access. 3) Educate users to avoid interacting with suspicious applications or prompts that could trigger the vulnerability. 4) Implement endpoint security solutions that monitor and restrict app behaviors related to notification access. 5) Review and tighten app permissions related to notifications and inter-device data sharing within macOS settings. 6) For enterprises, consider deploying Mobile Device Management (MDM) policies to enforce updates and control app installations. 7) Monitor for unusual notification access patterns or local privilege escalations that could indicate exploitation attempts. These steps go beyond generic patching by emphasizing user awareness, permission management, and proactive endpoint security controls.