CVE-2026-86910: Apple macOS Path Traversal Vulnerability

CVE-2026-86910 Overview

CVE-2026-86910 is a permissions vulnerability in Apple macOS caused by insufficient path validation. An application running on an affected system can leverage the flaw to access files that should remain restricted by the operating system's sandbox and permission controls. Apple addressed the issue with improved path validation in macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7. The weakness is classified as a path traversal issue [CWE-22] and requires local access with user interaction to exploit.

Critical Impact
A local application may read restricted files on the file system, exposing sensitive user or system data protected by macOS access controls.

Affected Products

Apple macOS Golden Gate (prior to 27)
Apple macOS Sequoia (prior to 15.8)
Apple macOS Tahoe (prior to 26.7)

Discovery Timeline

2026-09-14 - CVE-2026-86910 published to the National Vulnerability Database
2026-09-18 - Last updated in NVD database

Technical Details for CVE-2026-86910

Vulnerability Analysis

CVE-2026-86910 is a path traversal weakness [CWE-22] in Apple macOS. The operating system performs permission checks against file paths supplied by applications, but the validation logic fails to fully normalize or canonicalize those paths before the access decision is made. As a result, an application can craft a request that resolves to a protected file after the check passes.

Apple's advisory describes the fix as "improved path validation," indicating that the patched code now canonicalizes and re-verifies the target path before granting access. Exploitation requires local execution on the host and some form of user interaction, which limits remote abuse but not post-compromise activity.

The issue affects confidentiality only. It does not permit modification of the accessed files or degrade system availability, per the CVSS vector published by Apple.

Root Cause

The root cause is inadequate normalization of file paths inside macOS permission enforcement logic. When an application supplies a path that traverses symbolic links, relative segments, or other indirection, the pre-check path and the resolved path diverge. The permission subsystem authorizes access based on the appearance of the path rather than its resolved target, allowing restricted files to be reached.

Attack Vector

An attacker must run code locally on the target macOS host, typically inside a sandboxed or otherwise permission-limited application. The attacker constructs a file path that bypasses macOS access checks and requests the resource through standard file APIs. User interaction, such as opening a malicious document or launching a signed but hostile application, is required to trigger the code path.

No public proof-of-concept exploit is available for CVE-2026-86910, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the Apple Support Document #149035, Apple Support Document #149042, and Apple Support Document #149043 for vendor technical details.

Detection Methods for CVE-2026-86910

Indicators of Compromise

Unexpected file read events targeting Transparency, Consent, and Control (TCC) protected directories such as ~/Library/Application Support, ~/Library/Mail, and ~/Documents from non-privileged applications.
Applications resolving paths that contain symbolic link traversal or .. segments immediately before accessing sensitive resources.
Sandboxed processes accessing files outside of their declared container without a corresponding user-granted entitlement.

Detection Strategies

Monitor Endpoint Security framework events (ES_EVENT_TYPE_NOTIFY_OPEN, ES_EVENT_TYPE_NOTIFY_READLINK) for applications reading files outside their sandbox scope.
Correlate process execution telemetry with file access telemetry to flag processes that open protected paths shortly after resolving symbolic links.
Baseline expected file-access patterns per application and alert on deviations, particularly for third-party apps touching Apple-protected directories.

Monitoring Recommendations

Ingest macOS Unified Logging and Endpoint Security telemetry into a centralized analytics platform for retrospective hunting.
Track macOS build numbers across the fleet to identify hosts still running versions prior to macOS Sequoia 15.8, macOS Tahoe 26.7, or macOS Golden Gate 27.
Alert on installations of unsigned or newly signed applications that immediately attempt to read restricted user data.

How to Mitigate CVE-2026-86910

Immediate Actions Required

Upgrade all macOS endpoints to macOS Golden Gate 27, macOS Sequoia 15.8, or macOS Tahoe 26.7 as appropriate for the hardware.
Inventory macOS hosts by build number and prioritize systems handling sensitive data or used by privileged users.
Restrict installation of untrusted third-party applications through mobile device management (MDM) policy while patching is in progress.

Patch Information

Apple released fixes in macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7. The patches implement improved path validation so that permission checks operate on the canonicalized target path. Deployment details are available in Apple Support Document #149035, Apple Support Document #149042, and Apple Support Document #149043.

Workarounds

Enforce Gatekeeper and notarization requirements to block execution of unsigned applications that could carry an exploit.
Use MDM configuration profiles to tighten TCC prompts and require explicit user approval for Full Disk Access requests.
Limit user accounts to standard privileges where feasible to reduce the value of files reachable through the flaw.

bash

# Verify installed macOS version against patched builds
sw_vers -productVersion
softwareupdate --list
sudo softwareupdate --install --all --restart