CVE-2026-86876 in iPadOS
Summary
by MITRE • 09/15/2026
An out-of-bounds write issue 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, visionOS 27, watchOS 27. A sandboxed process may be able to circumvent sandbox restrictions.
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Analysis
by VulDB Data Team • 09/15/2026
The disclosed vulnerability represents a critical memory safety defect characterized as an out-of-bounds write operation within the core system components of Apple's operating ecosystem. This type of flaw typically arises when software incorrectly calculates or validates array indices, buffer sizes, or pointer arithmetic during data processing operations. Instead of halting execution upon detecting that a write target exceeds the allocated memory boundaries, the application proceeds to overwrite adjacent memory locations. The resolution involves implementing rigorous bounds checking mechanisms that validate all access requests against predefined limits before allowing any modification to occur in memory space. This technical fix ensures that processes cannot inadvertently or maliciously corrupt data structures outside their intended allocation zones, thereby preserving the integrity of system resources and preventing potential exploitation vectors associated with heap corruption or stack smashing techniques.
The operational impact of this vulnerability is significant due to its interaction with sandboxing mechanisms designed to isolate applications from one another and from sensitive system files. In a typical mobile or desktop environment, processes operate under strict confinement rules that restrict their ability to read or write data outside specific directories or access certain APIs. However, an out-of-bounds write can be leveraged by a malicious actor running within a sandboxed context to manipulate memory structures in ways that bypass these restrictions. By carefully crafting input that triggers the buffer overflow condition, an attacker may overwrite control flow data such as return addresses or function pointers located adjacent to the vulnerable buffer. This manipulation allows for arbitrary code execution with elevated privileges, effectively breaking out of the restrictive sandbox environment and gaining unauthorized access to protected system resources, user data, or other applications running on the device.
From a classification perspective, this vulnerability aligns closely with Common Weakness Enumeration identifier CWE-787, which denotes an out-of-bounds write condition. The exploitation strategy described, where a confined process escalates privileges by circumventing sandbox restrictions, maps directly to MITRE ATT&CK technique T1055, specifically the sub-category related to Process Injection or Memory Manipulation for privilege escalation. Furthermore, the act of escaping confinement corresponds to techniques found under T1611, which covers Escape to Host if the vulnerability allows breaking out of a container or sandboxed environment into the underlying host system. These mappings highlight the severity of the issue not just as a memory corruption bug but as a potential pathway for significant security breaches in multi-tenant environments like iOS and macOS where user data isolation is paramount.
Mitigation strategies primarily rely on the deployment of the provided software updates which contain the corrected bounds checking logic. For system administrators and end-users, it is imperative to apply these patches immediately across all affected platforms including iOS 26.7, iPadOS 26.7, iOS 27, iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7, visionOS 27, and watchOS 27. Beyond patching, developers should adopt secure coding practices that emphasize input validation and memory safety checks during the software development lifecycle to prevent similar defects in future releases. Utilizing static analysis tools capable of detecting buffer overflow conditions and employing runtime protection mechanisms such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) can further reduce the likelihood of successful exploitation even if a vulnerability exists. Regular security audits and penetration testing focused on sandbox escape scenarios are also recommended to ensure that isolation boundaries remain robust against evolving attack techniques.