CVE-2026-84544 in macOS
Summary
by MITRE • 09/15/2026
An integer overflow was addressed with improved input validation. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. Connecting to a malicious NFS server may cause unexpected system termination or corrupt kernel memory.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves an integer overflow within the Network File System client implementation in Apple operating systems, specifically affecting versions prior to macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7. An integer overflow occurs when a calculation results in a numeric value that exceeds the maximum limit for a given data type, causing it to wrap around to a small negative or positive number rather than failing gracefully. In this context, the flaw likely resides within the parsing of NFS protocol messages where size fields or offset calculations are not adequately validated before being used in memory allocation functions or buffer operations. When an attacker controls these input values by connecting to a malicious NFS server, they can craft specific packets that trigger this arithmetic error during processing.
The operational impact of this vulnerability is severe due to its potential for remote code execution and system instability. Because the integer overflow affects kernel-level components responsible for handling file system requests, the resulting memory corruption can lead to unexpected system termination, commonly known as a kernel panic or denial of service. More critically, if an attacker carefully manipulates the overwritten memory regions through precise control of the overflowed values, they may achieve arbitrary code execution with kernel privileges. This grants full control over the affected device, allowing for data exfiltration, persistence mechanisms, and lateral movement within a network environment that relies on NFS services.
From a classification perspective, this issue aligns with CWE-190, which defines integer overflow or wraparound errors, often leading to subsequent vulnerabilities such as buffer overflows (CWE-787) if the corrupted size is used for memory allocation. In terms of adversary tactics, exploiting this vulnerability would fall under MITRE ATT&CK technique T1496, Resource Hijacking, particularly in the context of denial of service via system termination, or potentially T1055, Process Injection, if kernel-level code execution is achieved to inject malicious payloads into privileged processes. The attack vector requires network connectivity to a compromised NFS server, classifying it as an exploitable remote vulnerability that targets specific infrastructure services rather than general user applications.
Mitigation strategies primarily involve applying the provided software updates from Apple for macOS Golden Gate 27, Sequoia 15.8, and Tahoe 26.7, which include improved input validation logic to prevent invalid arithmetic operations from proceeding further in the processing pipeline. For environments where immediate patching is not feasible, network segmentation should be enforced to restrict NFS traffic to trusted servers only. Additionally, deploying intrusion detection systems capable of analyzing NFS protocol anomalies can help identify attempts to exploit this vulnerability by monitoring for unusually large or malformed packet sizes that might trigger the overflow condition before it reaches the kernel layer.