CVE-2026-43773 in macOS
Summary
by MITRE • 07/28/2026
An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, macOS Tahoe 26.6. Mounting a maliciously crafted disk image may cause unexpected system termination or corrupt kernel memory.
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Analysis
by VulDB Data Team • 07/28/2026
This vulnerability represents a critical out-of-bounds read flaw that was addressed through enhanced bounds checking mechanisms within the macOS operating system kernel. The issue manifests when the system attempts to process maliciously crafted disk images, creating conditions where improper memory access can occur during the mounting process. Such vulnerabilities fall under the common weakness enumeration CWE-129 which specifically addresses insufficient bound checking for buffer operations, making this a classic example of memory safety issues that can lead to system instability and potential exploitation.
The technical nature of this flaw involves kernel-level memory management where the system fails to properly validate array indices or memory access boundaries when handling disk image metadata. When a maliciously crafted disk image is mounted, the kernel's file system driver processes the image headers and structures without adequate bounds verification, potentially allowing an attacker to manipulate memory pointers beyond allocated buffer limits. This type of vulnerability can be categorized under ATT&CK technique T1059.003 for command and scripting interpreter usage in kernel contexts, though the primary risk lies in the memory corruption aspect rather than direct code execution.
The operational impact of this vulnerability extends beyond simple system crashes to include potential kernel memory corruption that could compromise system integrity and stability. When the system encounters malformed disk image structures, it may experience unexpected termination or more insidiously, corrupt kernel memory regions that could lead to privilege escalation opportunities or persistent system instability. The fix implemented in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, and macOS Tahoe 26.6 addresses this by strengthening the bounds checking mechanisms within the disk image mounting subsystem, ensuring proper validation of all memory access operations during file system processing.
Security practitioners should recognize this vulnerability as part of the broader category of kernel memory corruption issues that can be leveraged for privilege escalation attacks or system compromise. The mitigation strategy requires immediate deployment of the patched macOS versions across affected systems, particularly in enterprise environments where users may encounter untrusted disk images through various attack vectors including email attachments, web downloads, or removable media. Organizations should also implement additional controls such as disk image validation procedures and user education regarding suspicious file handling practices to minimize exposure risks associated with this class of vulnerability.