CVE-2026-86870 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, visionOS 27, watchOS 27. Processing a maliciously crafted file may lead to unexpected app termination.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described constitutes a heap buffer overflow, a critical class of memory corruption flaws that arise when a program writes data beyond the allocated boundaries of a heap-allocated buffer. This specific issue was resolved through improved bounds checking mechanisms within the affected Apple operating systems, including iOS 26.7 and iPadOS 26.7, as well as versions 27 across iOS, iPadOS, macOS Golden Gate, visionOS, and watchOS. The root cause lies in insufficient validation of input data lengths prior to memory operations, allowing an attacker-controlled payload to overwrite adjacent heap metadata or arbitrary memory locations. This type of flaw is formally categorized under CWE-122: Heap-based Buffer Overflow in the Common Weakness Enumeration standard, which highlights the danger of writing past the end of a dynamically allocated block of memory on the heap rather than the stack.
The operational impact of this vulnerability centers on the potential for denial-of-service conditions and potentially more severe exploitation vectors depending on the context of execution. As noted in the advisory, processing a maliciously crafted file can lead to unexpected application termination. This occurs because the out-of-bounds write corrupts critical heap structures or triggers memory protection mechanisms such as guard pages, causing the operating system to forcibly terminate the offending process to prevent further instability. While immediate exploitation for arbitrary code execution may require additional conditions like specific allocator states or adjacent vulnerable objects, the mere ability to crash an application represents a significant reliability and availability risk. In security frameworks like MITRE ATT&CK, this behavior aligns with techniques related to resource exhaustion and potential privilege escalation if the overflowed memory contains pointers that can be manipulated to redirect control flow.
Mitigation strategies primarily rely on the deployment of the provided software updates which patch the underlying code logic responsible for the insufficient bounds checking. For developers integrating similar file processing libraries, it is imperative to implement rigorous input validation before any allocation or copy operation occurs. This includes verifying file sizes against expected limits and ensuring that all read operations respect the allocated buffer size. Additionally, leveraging modern compiler features such as AddressSanitizer during development can help detect these types of memory errors early in the lifecycle. System administrators should ensure that devices running iOS, iPadOS, macOS Golden Gate, visionOS, or watchOS are updated to the latest patched versions to eliminate this attack surface and maintain system integrity against maliciously crafted file inputs.