CVE-2026-84565 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 disk image may lead to unexpected app termination.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves an out-of-bounds read condition within the system components responsible for processing disk images on Apple operating systems including macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7. An out-of-bounds read occurs when a software application attempts to access memory locations that lie outside the boundaries of the intended buffer or data structure. In this specific context, the flaw resides in the parsing logic used by the operating system to interpret disk image files. When the system processes a maliciously crafted disk image, it fails to properly validate the size and offset parameters associated with the file's internal structures before attempting to read from them. This lack of rigorous bounds checking allows an attacker to specify offsets that point to memory regions not allocated for the current operation, leading the application to retrieve data from unintended locations in system memory.
The primary operational impact of this vulnerability is a denial of service manifested through unexpected app termination or system instability. Because the out-of-bounds read involves accessing unauthorized memory segments, it typically triggers protection mechanisms such as segmentation faults or access violations within the operating kernel or associated user-space processes handling file I/O operations. This results in the abrupt crash of the application responsible for mounting or inspecting the disk image, and potentially affects other system services depending on how deeply the vulnerability penetrates the stack. While out-of-bounds reads are often precursors to more severe exploits such as information disclosure where sensitive memory contents might be leaked, the current description emphasizes termination rather than data exfiltration. However, the potential for further exploitation remains a critical concern if the read operation can be leveraged to leak kernel pointers or other confidential system state information that could aid in subsequent privilege escalation attacks.
From a classification perspective, this vulnerability aligns with CWE-125 Out-of-bounds Read as defined by the Common Weakness Enumeration standard. This category encompasses instances where software reads past the end of an allocated buffer due to insufficient validation of input parameters or boundary conditions. In terms of offensive security tactics, this flaw could be leveraged within the MITRE ATT&CK framework under techniques related to Initial Access via malicious files or potentially Defense Evasion if used to crash security monitoring agents. The attack vector is local but can be triggered remotely if a user is persuaded to open a crafted disk image through phishing or other social engineering tactics, making it relevant for threat models involving targeted attacks against macOS environments.
Mitigation strategies primarily involve the deployment of the provided software updates which address the root cause by implementing improved bounds checking within the disk image processing subsystems. Administrators and users should ensure that their systems are updated to at least macOS Golden Gate 27, macOS Sequoia 15.8, or macOS Tahoe 26.7 depending on their current version lineage. Beyond patching, defensive measures include restricting the execution of untrusted scripts and disabling automatic mounting features for removable media where feasible to reduce the attack surface. Security awareness training should also emphasize caution when opening disk image files from unknown sources, as these remain a common vector for delivering malicious payloads that exploit such low-level system vulnerabilities. Continuous monitoring for unusual process terminations or kernel panics related to file I/O operations can help in detecting attempted exploitation of this flaw before it leads to significant operational disruption.