CVE-2026-43763: Apple macOS Information Disclosure Flaw

CVE-2026-43763 Overview

CVE-2026-43763 is a permissions issue affecting Apple macOS that allows a local application to read files outside of its sandbox. Apple addressed the flaw by removing the vulnerable code in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, and macOS Tahoe 26.6. The vulnerability is categorized under [CWE-284] (Improper Access Control) and requires local access with user interaction to exploit. Successful exploitation results in unauthorized disclosure of file contents that should be isolated by the macOS sandbox.

Critical Impact
A malicious application installed on macOS can bypass sandbox restrictions and read files belonging to other apps or system components, exposing sensitive user data.

Affected Products

Apple macOS Sequoia versions prior to 15.7.8
Apple macOS Sonoma versions prior to 14.8.8
Apple macOS Tahoe versions prior to 26.6

Discovery Timeline

2026-07-27 - CVE-2026-43763 published to NVD
2026-07-28 - Last updated in NVD database

Technical Details for CVE-2026-43763

Vulnerability Analysis

CVE-2026-43763 is an improper access control flaw [CWE-284] in macOS. The App Sandbox is a macOS security control that restricts what files, resources, and system services a running application can access. This vulnerability breaks that boundary by allowing a sandboxed application to read files outside its designated container.

Apple's advisory states the issue was "addressed by removing the vulnerable code," indicating the affected functionality was deprecated rather than reworked. Attackers can leverage the flaw to harvest sensitive files, including data from other applications, user documents, or configuration material that should remain isolated.

Exploitation requires local execution on the target system and user interaction, such as launching a malicious application. No network vector is available, and integrity or availability of the system is not directly impacted, though confidentiality loss can be significant.

Root Cause

The root cause is an improper permissions check in a macOS component that allowed sandboxed code to reach files outside its assigned container. Because Apple's remediation was to remove the vulnerable code entirely, the flaw resides in functionality that was determined to be non-essential or unsafe to retain. Refer to the Apple Support Article #128067, Apple Support Article #128071, and Apple Support Article #128072 for vendor detail.

Attack Vector

An attacker must deliver and execute a crafted application on the target macOS system. Once the user runs the app, sandbox restrictions can be bypassed to read files outside the app container. Distribution paths include social engineering, trojanized installers, or malicious binaries delivered through unvetted download channels. See vendor advisories for technical details; no public proof-of-concept code is available at this time.

Detection Methods for CVE-2026-43763

Indicators of Compromise

Unsigned or ad-hoc signed applications running from user-writable locations such as ~/Downloads or /tmp
Sandboxed processes issuing file reads to paths outside their container (for example, other apps' Containers directories, ~/Library/Application Support/, or user documents they were not granted access to)
Applications accessing sensitive files shortly after first launch with no clear user-driven action

Detection Strategies

Monitor Endpoint Security framework events (ES_EVENT_TYPE_NOTIFY_OPEN, ES_EVENT_TYPE_NOTIFY_READDIR) for sandboxed processes accessing paths outside their container root
Correlate application code-signing identifiers with observed file access patterns to identify anomalous cross-container reads
Alert on macOS versions still running vulnerable builds (below 15.7.8, 14.8.8, or 26.6) via inventory queries

Monitoring Recommendations

Ingest macOS Unified Logs and Endpoint Security telemetry into a centralized analytics platform for behavioral baselining
Track process-to-file relationships for signed applications to identify deviations from expected sandbox boundaries
Review installed applications and their entitlements periodically to identify apps with excessive or unusual entitlement claims

How to Mitigate CVE-2026-43763

Immediate Actions Required

Upgrade macOS Sequoia hosts to version 15.7.8 or later
Upgrade macOS Sonoma hosts to version 14.8.8 or later
Upgrade macOS Tahoe hosts to version 26.6 or later
Audit installed applications and remove any from untrusted sources

Patch Information

Apple released fixes in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, and macOS Tahoe 26.6. Patch details are documented in Apple Support Article #128067, Apple Support Article #128071, and Apple Support Article #128072. Apply updates through System Settings or MDM as soon as feasible.

Workarounds

Restrict application installation to those from the Mac App Store or identified developers via Gatekeeper policy
Enforce MDM configuration profiles that block execution of unsigned binaries
Educate users to avoid launching untrusted applications until systems are patched

bash

# Verify current macOS version and confirm it meets the patched build
sw_vers -productVersion

# Trigger available Apple software updates
sudo softwareupdate --install --all --restart

# Enforce Gatekeeper to allow only App Store and identified developers
sudo spctl --master-enable