CVE-2026-84518 in iOS
Summary
by MITRE • 09/15/2026
This issue was addressed through improved state management. This issue is fixed in Safari 27, iOS 27 and iPadOS 27, macOS Golden Gate 27. A malicious website may be able to determine what apps a user has installed.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves a flaw in the state management mechanisms within Apple's WebKit engine, which powers Safari on iOS, iPadOS, and macOS platforms. This issue allows for potential information disclosure by enabling a malicious web page to infer or determine the specific applications installed on a user's device. The root cause lies in how browser states are handled during interactions with certain APIs or internal system calls that may inadvertently leak metadata about local application installations. Such state management errors often arise when developers fail to properly isolate browsing contexts from sensitive system-level information, allowing cross-context data leakage through timing attacks, resource loading behaviors, or error message variations.
From a technical perspective, this type of vulnerability typically exploits the browser's ability to interact with native operating systems via JavaScript APIs like registerProtocolHandler, custom URL schemes, or deep linking mechanisms. When these interactions are not strictly sandboxed or when their responses vary based on whether an associated application is present, attackers can construct scripts that probe for specific app identifiers. By analyzing response times, HTTP status codes, or DOM changes triggered by failed attempts to open non-existent apps versus successful ones, a malicious site can build a profile of the user's installed software ecosystem without explicit permission. This represents a significant privacy concern as it bypasses standard consent models and operating system permissions that normally restrict such access.
The operational impact of this vulnerability is primarily centered around user privacy erosion rather than direct device compromise or data theft. An attacker leveraging this flaw could gather intelligence on the security posture, productivity tools, communication platforms, or financial applications a target uses. This information can be used to tailor subsequent phishing campaigns, social engineering attacks, or targeted exploits that exploit vulnerabilities specific to those installed applications. For instance, knowing a user has a particular email client or banking app allows an attacker to craft highly convincing malicious links designed to trigger known flaws in those specific apps. While the browser itself remains secure from code execution, the leakage of application inventory constitutes a serious breach of confidentiality and undermines the principle of least privilege expected in modern web browsing environments.
Industry standards classify this type of issue under CWE-200: Information Exposure, specifically where sensitive information is derived from side channels or improper state handling rather than direct database queries. In terms of the MITRE ATT&CK framework, this behavior aligns with T1598: Phishing for Information and potentially T1614: System Location Discovery if it contributes to broader reconnaissance efforts. The vulnerability highlights the ongoing challenge in web security where convenience features like deep linking must be balanced against strict privacy boundaries. Developers must ensure that any interaction between web content and native applications does not reveal metadata about system configuration unless explicitly authorized by the user through robust permission dialogs.
Mitigation strategies involve both technical fixes within the browser engine and defensive practices for developers and users. Apple has addressed this in Safari 27, iOS 27, iPadOS 27, and macOS Golden Gate 27 by improving state management to prevent such inference attacks. For organizations relying on older versions of these operating systems, it is critical to prioritize patching schedules to ensure all devices are updated to the latest secure releases. Additionally, web developers should avoid implementing custom URL scheme handlers that do not require user confirmation and should design fallback behaviors for missing apps in a way that does not expose timing or status differences. Users can further mitigate risk by regularly reviewing app permissions granted to websites and disabling unnecessary protocol handler registrations within their browser settings. Continuous monitoring of security advisories from Apple is essential, as such state management flaws may persist across different components until comprehensive architectural reviews are conducted.