CVE-2026-84597 in iOS
Summary
by MITRE • 09/15/2026
An out-of-bounds read issue was addressed with improved input validation. This issue is fixed in iOS 27 and iPadOS 27, macOS Golden Gate 27, tvOS 27, visionOS 27, watchOS 27. Processing a maliciously crafted font may result in the disclosure of process memory.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described constitutes an out-of-bounds read condition within the system's font processing subsystem, specifically affecting iOS, iPadOS, macOS, tvOS, visionOS, and watchOS versions prior to their respective 27th major releases. This class of defect arises when the application fails to adequately validate input data before accessing memory buffers associated with font rendering or parsing operations. In this specific instance, the flaw is triggered by processing a maliciously crafted font file that contains malformed structures or unexpected metadata values. When the system attempts to parse these irregularities, it reads beyond the allocated boundaries of the intended buffer, leading to an out-of-bounds read scenario. This behavior indicates a fundamental failure in input validation mechanisms designed to ensure that all data accessed during font processing remains within strictly defined memory limits established by the application's allocation routines.
From a technical perspective, this vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-125, which defines out-of-bounds read vulnerabilities where software reads past the end of an allocated buffer. The operational impact of such a flaw is significant because it allows for the disclosure of process memory contents to an attacker who can supply the malicious font file. By exploiting this condition, an adversary may be able to extract sensitive information residing in adjacent memory locations that were not intended to be accessed by the font processing routine. This could include cryptographic keys, session tokens, or other confidential data stored within the application's address space. The ability to leak process memory undermines the confidentiality guarantees provided by modern operating system sandboxing and isolation mechanisms, potentially facilitating further exploitation chains such as information disclosure leading to privilege escalation or remote code execution if combined with additional vulnerabilities in adjacent components.
In terms of threat modeling and attack taxonomy, this vulnerability maps to MITRE ATT&CK technique T1083, which covers File and Directory Discovery, although the primary impact here is more aligned with data exfiltration via memory leakage rather than simple file enumeration. It also relates to CWE-200, an exposure of sensitive information to an unauthorized actor. The exploitation typically requires user interaction or a specific trigger condition where the malicious font is processed by the system's rendering engine, such as when viewing a document, webpage, or message containing the crafted asset. This places the vulnerability in the context of client-side attacks where the victim must be induced to process untrusted content that interacts with core system libraries responsible for typography and layout management.
Apple has addressed this issue through improved input validation logic within the affected operating systems. The fix ensures that all font data is rigorously checked against expected bounds before any memory access occurs, thereby preventing the out-of-bounds read condition from being triggered. To mitigate the risk associated with such vulnerabilities in environments where updates may not be immediately applied, organizations should enforce strict content filtering policies to prevent untrusted fonts from entering their systems. Additionally, users and administrators are strongly advised to update all Apple devices to iOS 27, iPadOS 27, macOS Golden Gate 27, tvOS 27, visionOS 27, or watchOS 27 as soon as possible. Regular patching cycles remain the most effective defense against known memory corruption vulnerabilities that rely on parsing untrusted input data within system services.