CVE-2026-84577: Apple macOS Auth Bypass Vulnerability

CVE-2026-84577 Overview

CVE-2026-84577 is a sandbox bypass vulnerability affecting Apple macOS. An application running under the macOS sandbox can circumvent restrictions and access resources outside its intended boundary. Apple addressed the issue by adding sandbox restrictions in macOS Golden Gate 27 and macOS Tahoe 26.7.

The underlying weakness is classified as [CWE-120] and requires local access with user interaction. Successful exploitation leads to a scope change, allowing an attacker-controlled app to reach data and functionality that should remain isolated from sandboxed processes.

Critical Impact
A malicious or compromised application can escape macOS sandbox controls and access sensitive user data or system components normally protected by the sandbox boundary.

Affected Products

Apple macOS versions prior to macOS Golden Gate 27
Apple macOS versions prior to macOS Tahoe 26.7
Applications relying on macOS App Sandbox for containment

Discovery Timeline

2026-09-14 - CVE-2026-84577 published to the National Vulnerability Database
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-84577

Vulnerability Analysis

The flaw is an access control weakness in the macOS App Sandbox enforcement layer. The sandbox is intended to constrain what an application can read, write, or execute through kernel-level policy checks. Apple's advisory states that additional sandbox restrictions were required to close the gap, indicating the previous policy did not fully mediate certain resource accesses.

Because the CVSS vector indicates a scope change with high confidentiality and integrity impact, a successful bypass affects resources beyond the vulnerable component itself. The attack requires local execution and user interaction, consistent with the app-launch model on macOS where a user runs or installs the offending application.

Root Cause

The root cause is insufficient sandbox policy coverage for a specific access path. A sandboxed process could reach protected resources without triggering the expected denial. Apple's fix strengthens the sandbox profile to enforce the missing restrictions in macOS Golden Gate 27 and macOS Tahoe 26.7.

Attack Vector

An attacker delivers a malicious application, or compromises an existing sandboxed application, and induces the user to run it. Once executing under the sandbox, the application invokes the affected code path to reach resources outside its container. The vulnerability does not permit remote exploitation and does not directly grant code execution as another user, but it undermines the isolation guarantees that other macOS security controls depend on.

No public proof-of-concept exploit is available. No entry exists in the CISA Known Exploited Vulnerabilities catalog. The EPSS probability is low, reflecting limited observed exploitation activity at publication.

Detection Methods for CVE-2026-84577

Indicators of Compromise

Sandboxed applications performing file access, IPC, or Mach service lookups outside their declared entitlements
Unexpected child processes spawned from applications delivered via the Mac App Store or notarized bundles
Anomalous access to user data directories such as ~/Library, ~/Documents, or Keychain files from sandboxed apps

Detection Strategies

Monitor Endpoint Security framework events (ES_EVENT_TYPE_NOTIFY_OPEN, ES_EVENT_TYPE_NOTIFY_EXEC) for sandboxed processes touching resources outside their container
Correlate sandboxd and kernel log entries reporting deny decisions with successful follow-on access to the same resource
Baseline entitlements per application and alert on runtime behavior that exceeds declared com.apple.security.* entitlements

Monitoring Recommendations

Enable unified logging with the com.apple.sandbox subsystem and forward events to a central analytics platform
Track macOS version inventory to identify endpoints still running builds prior to macOS Golden Gate 27 and macOS Tahoe 26.7
Review installed applications for unsigned or ad-hoc signed bundles that request broad entitlements

How to Mitigate CVE-2026-84577

Immediate Actions Required

Upgrade affected endpoints to macOS Golden Gate 27 or macOS Tahoe 26.7 per the Apple Security Advisory #149035 and Apple Security Advisory #149042
Audit installed third-party applications and remove software from untrusted sources
Enforce Gatekeeper and notarization requirements on all managed Macs

Patch Information

Apple resolved the issue by adding sandbox restrictions in macOS Golden Gate 27 and macOS Tahoe 26.7. Refer to the Apple Security Advisory #149035 and Apple Security Advisory #149042 for the complete list of fixed components and download instructions.

Workarounds

Restrict installation of new applications through mobile device management (MDM) policies until patches are deployed
Require user consent prompts for applications requesting access to sensitive directories via Transparency, Consent, and Control (TCC)
Remove or disable non-essential sandboxed applications that request broad file-system or IPC entitlements

bash

# Verify installed macOS build version on a managed endpoint
sw_vers -productVersion

# Query MDM inventory for endpoints below the patched builds
# Replace with your MDM's query syntax
mdmctl query --os macOS --version-below 26.7