CVE-2026-43761 in macOS
Summary
by MITRE • 09/15/2026
An out-of-bounds write issue 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 malicious disk image may cause unexpected system termination.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves an out-of-bounds write condition within the macOS operating system's handling of mounted disk images. This type of memory corruption flaw typically arises when software fails to properly validate input data before writing it to allocated memory buffers, allowing a malicious actor to overwrite adjacent memory locations with arbitrary values. In this specific instance, the issue was addressed by implementing improved bounds checking mechanisms that ensure write operations remain strictly within the boundaries of the intended buffer space. The absence of such checks previously allowed crafted disk image files to trigger writes beyond the allocated memory region, leading to undefined behavior and potential system instability.
The operational impact of exploiting this vulnerability is significant for local users who interact with untrusted storage media. By mounting a maliciously constructed disk image, an attacker can induce unexpected system termination, effectively causing a denial-of-service condition against the affected macOS devices running versions prior to macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, and macOS Tahoe 26.6. While immediate exploitation for arbitrary code execution may require additional conditions such as specific memory layouts or further vulnerabilities in adjacent processes, the guaranteed system crash represents a severe availability risk. This aligns with Common Weakness Enumeration (CWE) category CWE-787: Out-of-bounds Write, which highlights the danger of writing data outside the bounds of a buffer due to insufficient validation of input lengths and indices.
From an attack vector perspective, this vulnerability is classified under MITRE ATT&CK technique T1496: Resource Hijacking, specifically within the sub-technique for Denial of Service via resource exhaustion or system instability caused by memory corruption attacks. The requirement to mount a disk image indicates that physical access or the ability to trick a user into mounting a malicious volume is necessary, placing it in the Local category with potential for privilege escalation if combined with other flaws. To mitigate this risk, administrators and users should ensure their systems are updated to the specified patched versions where the bounds checking logic has been reinforced. Additionally, enforcing strict policies on auto-mounting removable media and using endpoint detection solutions that monitor for abnormal memory access patterns can provide additional layers of defense against exploitation attempts involving crafted disk images or other storage-based attack vectors.