CVE-2026-43819: Apple macOS Information Disclosure Flaw

CVE-2026-43819 Overview

CVE-2026-43819 is an access control weakness in Apple macOS that allows a local application to reach sensitive user data. Apple resolved the issue in macOS Tahoe 26.6 by tightening sandbox restrictions on the affected component. The flaw is classified under [CWE-284] Improper Access Control and requires local access with user interaction to exploit. Confidentiality is the primary impact, while integrity and availability are not affected. The vulnerability affects Apple macOS installations prior to the fixed release.

Critical Impact
A malicious or compromised application running locally can bypass sandbox boundaries to read sensitive user data without additional privileges.

Affected Products

Apple macOS versions prior to macOS Tahoe 26.6
Applications relying on the affected sandbox profile
macOS endpoints running unpatched builds

Discovery Timeline

2026-07-27 - CVE-2026-43819 published to NVD
2026-07-28 - Last updated in NVD database

Technical Details for CVE-2026-43819

Vulnerability Analysis

CVE-2026-43819 stems from an improper access control condition in the macOS sandbox enforcement layer. The sandbox failed to fully constrain an application's ability to reach data outside its allowed container. As a result, an app with only standard user privileges could read sensitive user files or artifacts intended to remain isolated. Apple addressed the flaw by introducing additional sandbox restrictions in macOS Tahoe 26.6.

The attack requires local execution and user interaction, meaning a user must run or install the malicious application. No elevated privileges are required, and the scope remains unchanged. The vulnerability does not permit code execution or data modification directly, but exposed data can support downstream attacks such as credential harvesting, targeted phishing, or lateral movement.

EPSS data lists the exploitation probability as low, and no public proof-of-concept or in-the-wild exploitation has been reported.

Root Cause

The root cause is an insufficient sandbox policy that allowed an application to access resources it should not have been permitted to read. The fix adds explicit sandbox restrictions to close the gap. This aligns with [CWE-284], where the access control mechanism does not adequately restrict resources from unauthorized actors.

Attack Vector

An attacker delivers a crafted application to a target macOS system through standard software delivery channels such as email, downloads, or supply-chain compromise. The user launches the application, which then invokes the affected APIs or file paths to extract sensitive user data. See the Apple Support Article for the vendor's technical summary.

Detection Methods for CVE-2026-43819

Indicators of Compromise

Unsigned or newly installed applications accessing user data directories such as ~/Library, ~/Documents, or Keychain-related paths outside their declared entitlements.
Unexpected sandboxd policy violations or repeated denials in unified logs correlated with a single process.
Outbound network traffic from a recently launched application transmitting archives or serialized user data.

Detection Strategies

Monitor macOS unified logs (log show --predicate 'subsystem == "com.apple.sandbox"') for anomalous access attempts by non-system binaries.
Baseline application entitlement usage and alert when apps read files outside their expected scope.
Correlate process execution telemetry with file access events to identify sandbox boundary probing.

Monitoring Recommendations

Track macOS build versions across the fleet and flag hosts below macOS Tahoe 26.6.
Alert on execution of applications lacking valid notarization or signed by unknown developer IDs.
Review Endpoint Security Framework events for ES_EVENT_TYPE_NOTIFY_OPEN calls against sensitive user data paths from non-Apple processes.

How to Mitigate CVE-2026-43819

Immediate Actions Required

Upgrade all macOS endpoints to macOS Tahoe 26.6 or later using MDM-driven deployment.
Audit installed applications and remove untrusted or unsigned software.
Enforce Gatekeeper and notarization requirements to block execution of unverified applications.

Patch Information

Apple resolved CVE-2026-43819 in macOS Tahoe 26.6 by adding sandbox restrictions to the affected component. Details are published in the Apple Support Article. Administrators should validate the OS build via sw_vers -productVersion after deployment.

Workarounds

Restrict installation of third-party applications to vetted sources through MDM configuration profiles.
Enable Full Disk Access review and remove entitlements from applications that do not require them.
Educate users to avoid running applications from unknown developers until the patch is applied.

bash

# Verify macOS version meets the fixed build
sw_vers -productVersion

# Trigger a managed software update via MDM tooling (example: softwareupdate)
sudo softwareupdate --install --all --restart