CVE-2026-43687 in iOS
Summary
by MITRE • 09/15/2026
The issue was addressed with improved memory handling. This issue is fixed in iOS 26.7 and iPadOS 26.7, iOS 27 and iPadOS 27, macOS Golden Gate 27, macOS Tahoe 26.7, tvOS 27, visionOS 27, watchOS 27. Connecting to a malicious NFS server may disclose kernel memory.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves a critical flaw in the implementation of Network File System (NFS) client functionality within Apple operating systems, specifically affecting iOS, iPadOS, macOS, tvOS, visionOS, and watchOS versions prior to those listed as fixed. The core technical issue stems from improper memory handling during the processing of responses or data structures received from an NFS server. In a typical NFS interaction, the client sends requests for file operations such as reading directories or retrieving attributes, and the server responds with structured data packets. If the client software fails to adequately validate the length fields, bounds, or integrity of these incoming network packets before copying them into kernel memory buffers, it can lead to an out-of-bounds write or a buffer overflow condition. This type of flaw allows for arbitrary code execution potential if exploited correctly, but in this specific instance, the primary consequence identified is information disclosure through kernel memory exposure.
When a user's device connects to a malicious NFS server that has been crafted to send specially malformed packets, the vulnerability triggers during the parsing phase within the operating system's kernel. The flawed memory handling logic fails to properly restrict access or copy data beyond its intended boundaries, resulting in sensitive portions of the kernel's virtual address space being leaked back through the network response mechanism or exposed via subsequent crashes that dump memory contents. Kernel memory often contains highly privileged information including cryptographic keys, session tokens, process identifiers, and other security-critical structures. The disclosure of this data can provide an attacker with significant insights into the system's internal state, potentially facilitating further attacks such as privilege escalation or bypassing existing security controls like ASLR (Address Space Layout Randomization) by revealing memory layout addresses.
From a threat modeling perspective, this vulnerability aligns closely with CWE-120 Buffer Copy without Checking Size of Input and CWE-200 Exposure of Sensitive Information to an Unauthorized Actor. The attack vector is classified as Network-based under the MITRE ATT&CK framework, specifically falling within techniques related to Remote Services exploitation. An attacker does not need physical access or local user privileges; instead, they can exploit this flaw remotely by enticing a victim device to connect to their controlled NFS server. This could occur in enterprise environments where devices mount network shares for file synchronization, or even on personal devices if users are tricked into connecting to untrusted networks that offer NFS services. The impact is severe because it compromises the confidentiality of kernel-level data, which forms the foundation of trust and security isolation within modern operating systems.
Mitigation strategies primarily rely on applying the software updates provided by Apple for iOS 26.7, iPadOS 26.7, iOS 27, iPadOS 27, macOS Golden Gate 27, macOS Tahoe 26.7, tvOS 27, visionOS 27, and watchOS 27. These updates contain the necessary code changes to improve memory handling routines within the NFS client implementation, ensuring that input validation is rigorous and buffer operations are strictly bounded. In environments where immediate patching is not feasible, administrators should restrict network access to trusted NFS servers only, utilizing firewalls or network segmentation policies to prevent devices from connecting to untrusted or external NFS endpoints. Additionally, disabling unnecessary file sharing services on end-user devices can reduce the attack surface by eliminating the code path that triggers this vulnerability entirely until patches are deployed.