CVE-2025-43204: Apple macOS Privilege Escalation Vulnerability

CVE-2025-43204 Overview

CVE-2025-43204 is a sandbox escape vulnerability affecting Apple macOS. An application running within the macOS sandbox can break out of its containment boundary and access resources outside its permitted scope. Apple addressed the issue by removing the vulnerable code in macOS Tahoe 26.

The vulnerability is categorized under [CWE-284] (Improper Access Control). Exploitation requires local access and user interaction, but successful exploitation yields high impact to confidentiality, integrity, and availability. No public proof-of-concept exploit or in-the-wild exploitation has been confirmed.

Critical Impact
A malicious or compromised sandboxed application can escape its sandbox restrictions on macOS systems prior to macOS Tahoe 26, enabling access to user data and system resources outside the sandbox boundary.

Affected Products

Apple macOS (versions prior to macOS Tahoe 26)
Applications relying on the macOS sandbox for isolation
Third-party software distributed through the Mac App Store with sandbox entitlements

Discovery Timeline

2025-09-15 - CVE-2025-43204 published to the National Vulnerability Database
2025-09-15 - Apple releases macOS Tahoe 26 with the fix
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-43204

Vulnerability Analysis

The macOS sandbox is a kernel-level access control mechanism that restricts an application's ability to interact with the file system, network, inter-process communication channels, and other operating system resources. Applications opt into the sandbox through entitlements and a profile defining the permitted operations.

CVE-2025-43204 allows a sandboxed process to perform actions outside the boundaries enforced by its sandbox profile. Apple's advisory states the issue was resolved by removing the vulnerable code path entirely, indicating the affected component was non-essential to sandbox functionality. The vulnerability falls under the improper access control weakness class.

The attack vector is local with low complexity, no privileges required, and user interaction needed. This profile aligns with scenarios where a user launches a malicious application or opens malicious content within a legitimate sandboxed application.

Root Cause

The root cause is improper access control within a macOS component that exposed functionality reachable from within the sandbox without enforcing the expected restrictions. Apple has not disclosed the specific subsystem. Because the fix removed the vulnerable code rather than adding additional checks, the affected code path was likely legacy or rarely used functionality whose removal carried no compatibility cost.

Attack Vector

An attacker delivers a malicious application or content processed by a sandboxed application. After the user interacts with the application, the sandboxed process invokes the vulnerable code path. This invocation results in operations being executed outside the sandbox's intended boundary, allowing access to files, IPC endpoints, or system services that the sandbox profile should have blocked.

The vulnerability mechanism is described in prose because no verified proof-of-concept code is publicly available. See the Apple Support Article and Full Disclosure Mailing List Post for additional technical references.

Detection Methods for CVE-2025-43204

Indicators of Compromise

Sandboxed applications spawning child processes or accessing file paths outside their container directory under ~/Library/Containers/
Unexpected xpc or Mach service connections originating from processes with active sandbox entitlements
Sandboxed processes writing to system locations such as /Library/LaunchAgents/ or /Library/LaunchDaemons/

Detection Strategies

Monitor Apple Endpoint Security framework events for ES_EVENT_TYPE_NOTIFY_EXEC and file operations where the source process has the com.apple.security.app-sandbox entitlement but targets paths outside its container
Audit Unified Logging for sandbox violation messages from the sandboxd subsystem that precede successful operations on restricted resources
Correlate process execution telemetry with code signing entitlements to flag deviations from expected behavior

Monitoring Recommendations

Enable verbose sandbox violation logging through sysctl and forward sandboxd logs to a centralized analysis platform
Track macOS build and version inventory to identify endpoints running versions prior to macOS Tahoe 26
Baseline normal sandboxed application behavior so deviations such as new XPC connections or filesystem access trigger investigation

How to Mitigate CVE-2025-43204

Immediate Actions Required

Upgrade affected macOS endpoints to macOS Tahoe 26 or later, which contains the official fix
Audit installed third-party applications and remove software from untrusted sources that requests broad entitlements
Restrict installation privileges so that standard users cannot install unsigned or notarization-failed applications

Patch Information

Apple resolved CVE-2025-43204 in macOS Tahoe 26 by removing the vulnerable code. Refer to the Apple Support Article for the complete advisory and the list of components updated in this release. No backported patch is documented for earlier macOS major versions in the published advisory.

Workarounds

Limit execution to applications signed and notarized by trusted developers using Gatekeeper policy enforcement
Configure mobile device management (MDM) profiles to block installation of applications outside the Mac App Store on managed fleets
Apply the principle of least privilege by removing unnecessary entitlements from in-house applications and reviewing entitlements of third-party software

bash

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

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

# List sandboxed processes currently running
codesign -d --entitlements - /Applications/ExampleApp.app 2>&1 | \
  grep -A1 'com.apple.security.app-sandbox'