CVE-2026-43679 in watchOS
Summary
by MITRE • 08/21/2026
This issue was addressed with improved permissions checking. This issue is fixed in watchOS 26.4. An attacker with physical access to a locked Apple Watch may be able to view user contacts.
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Analysis
by VulDB Data Team • 08/21/2026
The vulnerability described involves an insufficient permission check within the operating system of the Apple Watch, specifically affecting versions prior to watchOS 26.4. This flaw allows for unauthorized data exposure by bypassing standard security controls that are designed to protect sensitive personal information when the device is in a locked state. The core technical issue lies in the application logic responsible for rendering or accessing user contact lists; rather than strictly enforcing access control policies based on the authentication status of the current session, the system permits read operations even when the device has not been unlocked by an authorized user. This represents a failure to properly validate privileges before granting access to protected resources, which is a classic example of broken access control where the software fails to enforce intended restrictions on authenticated or unauthenticated users depending on the specific implementation details of the lock screen interface.
From a technical perspective, this flaw aligns with CWE-269, Improper Privilege Management, as it involves a situation where an actor is able to perform actions that exceed their assigned privileges. Furthermore, because the vulnerability requires physical access to the device and exploits the state between locking and unlocking or during specific interactions on the lock screen, it can be categorized under ATT&CK technique T1539, Steal Web Session Cookie, although in this context it is more accurately mapped to data exfiltration from local storage rather than network sessions. The attacker leverages physical proximity to interact with the device's interface, potentially exploiting race conditions or logic errors in how the operating system handles temporary UI states before full authentication verification completes. This allows the extraction of contact information which may include names, phone numbers, and email addresses associated with the victim’s social and professional network.
The operational impact of this vulnerability is significant due to the sensitive nature of the exposed data. Contact lists often serve as a primary vector for further attacks such as spear-phishing or social engineering campaigns. An attacker who gains access to these details can craft highly personalized messages that appear legitimate, increasing the likelihood of success in subsequent phishing attempts against the victim or their colleagues. Additionally, the exposure of personal contact information violates user privacy expectations and may contravene data protection regulations depending on the jurisdiction and context of use. The risk is exacerbated by the fact that smartwatches are frequently worn during daily activities, making them susceptible to opportunistic attacks in public spaces where physical access can be gained briefly without immediate detection.
Mitigation for this vulnerability was implemented through improved permissions checking within watchOS 26.4. This update ensures that any request to display or retrieve contact data is rigorously validated against the current authentication state of the device. Developers and system architects should review similar implementations in other wearable devices to ensure that sensitive data access is strictly gated behind successful user verification mechanisms such as passcode entry, biometric confirmation, or paired trusted device authorization. Users are advised to update their watchOS software immediately upon availability to patch this flaw. In environments where physical security cannot be guaranteed, enabling additional lock screen restrictions and ensuring the auto-lock feature engages promptly can further reduce the window of opportunity for attackers attempting to exploit such logic errors.