CVE-2026-86940: macOS Golden Gate Information Disclosure

CVE-2026-86940 Overview

CVE-2026-86940 is an information disclosure vulnerability in Apple macOS that allows a local application to read kernel memory contents. Apple addressed the issue by removing the vulnerable code in macOS Golden Gate 27. The flaw is classified under [CWE-200] (Exposure of Sensitive Information to an Unauthorized Actor) and requires local access with low privileges to exploit. Successful exploitation exposes kernel memory contents that may include cryptographic material, pointers useful for bypassing Kernel Address Space Layout Randomization (KASLR), or other sensitive runtime data.

Critical Impact
A local application can disclose kernel memory on affected macOS systems, potentially leaking sensitive data and weakening kernel-level mitigations that defend against further exploitation.

Affected Products

Apple macOS versions prior to Golden Gate 27
Applications executing locally on affected macOS systems
Kernel-space memory regions reachable from user-mode interfaces

Discovery Timeline

2026-10-20 - CVE-2026-86940 published to the National Vulnerability Database
2026-10-20 - Last updated in NVD database

Technical Details for CVE-2026-86940

Vulnerability Analysis

The vulnerability allows a locally running application to disclose kernel memory contents through a flaw in macOS kernel code paths. Apple's advisory indicates the fix removed the vulnerable code entirely rather than refactoring it, suggesting the affected routine was non-essential or redundant. Kernel memory disclosures of this class typically arise from uninitialized stack or heap buffers copied to user space, structure padding leaks, or improper bounds handling in copy routines.

The attack surface is confined to local, authenticated contexts. However, the confidentiality impact is high because kernel memory may contain pointers that defeat KASLR, credentials, or data belonging to other processes. Attackers frequently chain information disclosure primitives with memory corruption bugs to achieve reliable privilege escalation.

Root Cause

The root cause is classified as [CWE-200], an information exposure flaw in a macOS kernel component. Apple's remediation strategy, removal of the vulnerable code, indicates the leaking code path was not required for system functionality. The specific component and leak mechanism are not publicly disclosed in the Apple advisory.

Attack Vector

Exploitation requires a local attacker to execute an application on the target macOS system. No user interaction is needed beyond running the malicious binary. The attacker invokes the vulnerable kernel interface and receives kernel memory bytes in a response buffer or side channel. See the Apple Support Article for vendor-published details.

No verified proof-of-concept code is publicly available for this issue, and no synthetic exploitation code is provided here.

Detection Methods for CVE-2026-86940

Indicators of Compromise

Unexpected processes making repeated or anomalous system calls to kernel interfaces that return large or variable-length buffers
Unsigned or newly installed binaries performing low-level kernel introspection on macOS hosts
Process execution patterns on macOS endpoints that have not been upgraded to Golden Gate 27

Detection Strategies

Inventory macOS endpoints and flag any system running a build earlier than Golden Gate 27 as exposed to CVE-2026-86940
Monitor for unsigned applications and developer tools that invoke uncommon syscall or IOKit interfaces at high rates
Correlate local privilege escalation attempts with preceding information disclosure activity on the same host

Monitoring Recommendations

Collect macOS Endpoint Security Framework (ESF) telemetry for process execution, code signing status, and system extension loads
Alert on execution of binaries from user-writable directories that interact with kernel extensions or /dev interfaces
Retain audit logs long enough to support retrospective hunts once additional technical details on CVE-2026-86940 are published

How to Mitigate CVE-2026-86940

Immediate Actions Required

Upgrade all affected Mac systems to macOS Golden Gate 27 as the authoritative remediation for CVE-2026-86940
Prioritize patching for developer workstations, administrator endpoints, and systems that handle sensitive data
Restrict installation of untrusted applications until patching is complete across the managed fleet

Patch Information

Apple fixed the issue in macOS Golden Gate 27 by removing the vulnerable code. Administrators should deploy the update through Software Update, Apple Business Manager, or an enterprise mobile device management (MDM) platform. Vendor details are available in the Apple Support Article.

Workarounds

No vendor-supplied workaround is documented; patching to Golden Gate 27 is the required remediation
Enforce Gatekeeper, System Integrity Protection (SIP), and application allowlisting to limit execution of untrusted local binaries
Apply the principle of least privilege for interactive user accounts on macOS endpoints

bash

# Verify macOS version and trigger software update check
sw_vers -productVersion
sudo softwareupdate --list
sudo softwareupdate --install --all --restart