CVE-2026-84516 in macOS
Summary
by MITRE • 09/15/2026
An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. Processing a maliciously crafted file may result in unexpected app termination or 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 that arises from insufficient validation of input data boundaries within the affected macOS components. This type of flaw typically occurs when software processes external inputs, such as files or network packets, without adequately verifying that the requested access to memory does not exceed the allocated buffer limits. In this specific instance, the underlying issue was addressed by implementing improved bounds checking mechanisms, which ensure that any read operation remains strictly within the designated memory regions assigned to the application process. The absence of these checks previously allowed an attacker to craft malicious files designed to trigger reads beyond the intended data structures, leading to unpredictable behavior in the operating system's processing routines.
The operational impact of this vulnerability is significant due to its potential for both denial of service and information disclosure. When a user or automated system processes a maliciously crafted file that exploits this flaw, it can cause the affected application to terminate unexpectedly, resulting in a local denial of service condition where legitimate work may be lost or interrupted. More critically, the out-of-bounds read allows an attacker to access memory contents that are not intended for public consumption. This can lead to the disclosure of sensitive process memory, which may contain cryptographic keys, authentication tokens, personal user data, or other confidential information residing in the application's address space. Such leakage compromises the confidentiality and integrity guarantees provided by macOS security architectures, potentially enabling further exploitation chains if combined with other vulnerabilities.
From a classification perspective, this vulnerability aligns with CWE-125, which defines out-of-bounds read errors where software reads data past the end or before the beginning of the intended buffer. It also relates to CWE-20, improper input validation, as the root cause is the failure to properly verify that inputs conform to expected structural constraints before processing. In terms of offensive security frameworks like MITRE ATT&CK, this flaw facilitates techniques associated with Discovery and Collection, specifically allowing an adversary to gather sensitive information from a compromised system without direct access to persistent storage or network exfiltration channels initially. The exploitation vector is primarily local file-based, meaning the attacker typically needs some level of interaction with the victim's environment to deliver the malicious payload, such as through phishing emails containing attached documents or visiting compromised websites that trigger automatic downloads and processing.
Mitigation strategies for this vulnerability focus on both immediate patching and long-term defensive engineering practices. The primary remediation is to update affected systems to macOS Golden Gate 27, macOS Sequoia 15.8, or macOS Tahoe 26.7, as these versions contain the necessary code fixes that enforce strict memory boundary checks during file processing operations. Organizations should ensure their asset management systems are configured to detect and deploy these updates promptly across all endpoints running vulnerable versions of macOS. Additionally, implementing application control policies can restrict the execution of untrusted scripts or binaries that might attempt to exploit such flaws before patches are applied. For developers maintaining custom applications on macOS platforms, adhering to secure coding standards that emphasize rigorous input validation and memory safety checks is essential to prevent similar out-of-bounds conditions in future software releases. Regular security audits and static analysis tools can help identify potential boundary check failures early in the development lifecycle, reducing the attack surface for such vulnerabilities.