CVE-2026-84510 in iOS
Summary
by MITRE • 09/15/2026
A heap buffer overflow was addressed with improved bounds checking. This issue is fixed in iOS 26.7 and iPadOS 26.7, iOS 27 and iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. Mounting a maliciously crafted volume may lead to unexpected system termination.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves a heap buffer overflow within the operating systems iOS and iPadOS version 26.7 as well as versions 27, alongside macOS Golden Gate 27, Sequoia 15.8, and Tahoe 26.7. A heap buffer overflow occurs when a program writes data to a buffer on the heap beyond its allocated boundaries. This specific flaw likely stems from insufficient validation of input parameters or length checks during the processing of volume mount requests. When an application attempts to allocate memory for handling file system metadata or directory structures, it may fail to verify that the incoming data size matches the expected capacity of the destination buffer. Consequently, excess data overwrites adjacent memory locations on the heap, corrupting internal data structures such as allocation headers or pointers used by the memory manager.
The operational impact of this vulnerability is significant due to its potential for causing system instability and denial of service. As noted in the advisory, mounting a maliciously crafted volume can lead to unexpected system termination. This indicates that the overflow likely corrupts critical control data within the kernel or core system services responsible for handling storage devices. When these structures are compromised, the operating system may encounter fatal errors such as invalid memory access violations or corrupted stack traces, triggering an immediate crash or reboot of the device. While heap overflows can sometimes be exploited to achieve arbitrary code execution by manipulating function pointers or virtual table entries in user-space applications, the specific mention of system termination suggests that this particular instance primarily results in a denial-of-service condition through kernel panic or service failure rather than direct remote code execution at this stage.
From a threat modeling perspective, this vulnerability aligns with CWE-122, which defines heap-based buffer overflow as writing data past the end or beginning of a heap allocated buffer. The attack vector is classified under ATT&CK technique T1564, specifically related to host isolation evasion if the crash prevents security monitoring tools from logging events, though more directly it falls under resource exhaustion leading to denial of service. An attacker would need physical access or network access to present a malicious storage device formatted with specially crafted file system structures that trigger the overflow condition during the mount operation. This requires the victim user or administrator to initiate the mounting process, making social engineering potentially relevant if the attack relies on convincing users to connect untrusted drives.
Mitigation strategies primarily involve applying the provided software updates which address the issue through improved bounds checking. Developers must ensure that all buffer operations include rigorous validation of input lengths before copying data into allocated memory regions. Implementing safe string handling functions and utilizing static analysis tools during development can help detect such discrepancies early in the lifecycle. For end-users, it is critical to keep iOS, iPadOS, and macOS devices updated to the latest patched versions listed above. Additionally, users should exercise caution when connecting external storage media from unknown sources, as these could contain payloads designed to exploit this specific memory corruption flaw. Security teams should monitor for indicators of compromise related to unusual system crashes or kernel panics following interactions with removable drives, which may indicate attempted exploitation attempts against unpatched systems.