CVE-2025-43331: Apple macOS Information Disclosure Flaw

CVE-2025-43331 Overview

CVE-2025-43331 is a downgrade vulnerability in Apple macOS that allows a local application to access protected user data. Apple addressed the flaw by introducing additional code-signing restrictions in macOS Tahoe 26. The issue is categorized under [CWE-862] Missing Authorization, reflecting an authorization gap that permits unauthorized data access from a locally installed app.

The vulnerability requires local access with no user interaction or privileges, and impacts confidentiality of user data protected by macOS access controls.

Critical Impact
A malicious app installed on a macOS system may bypass Transparency, Consent, and Control (TCC) protections and read user data that should require explicit user authorization.

Affected Products

Apple macOS versions prior to macOS Tahoe 26
Systems where downgrade of signed components was possible
All Mac hardware running vulnerable macOS releases

Discovery Timeline

2025-09-15 - CVE-2025-43331 published to the National Vulnerability Database (NVD)
2025-09-15 - Apple publishes advisory in Apple Support Article 125110
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-43331

Vulnerability Analysis

The flaw is a downgrade issue in macOS that undermines code-signing enforcement. An attacker with local code execution can substitute or reference an older, signed component to bypass current authorization checks. This enables an application to reach protected user data that current macOS releases intend to gate behind TCC prompts and entitlement checks.

Apple's fix in macOS Tahoe 26 adds code-signing restrictions that reject the downgraded components. The change tightens the trust decision made when the system loads or evaluates signed binaries and resources, closing the authorization gap tracked under [CWE-862].

Root Cause

The root cause is insufficient version and signing constraint enforcement on components that participate in protected-data access decisions. Because older signed binaries retained a valid signature, the system honored them even when their behavior no longer satisfied current security policy. This missing authorization check let an app act with the privileges implied by the outdated component.

Attack Vector

Exploitation requires local access. An attacker delivers or installs an application on the target Mac, then leverages the downgrade path to interact with protected user data such as files, TCC-guarded resources, or user profile artifacts. No user interaction and no prior privileges are required for the app to trigger the flaw.

No public proof-of-concept exploit is listed for this CVE. Technical discussion is available on the Full Disclosure mailing list post.

Detection Methods for CVE-2025-43331

Indicators of Compromise

Presence of older, individually signed Apple system binaries or frameworks placed inside application bundles or user-writable locations.
Applications invoking legacy signed helpers instead of the system-provided components in /System/Library/.
Access to TCC-protected directories such as ~/Library/Application Support/, ~/Documents/, or ~/Library/Messages/ by apps without corresponding user consent entries.

Detection Strategies

Inventory installed applications and flag bundles that ship copies of Apple-signed binaries from prior macOS versions.
Monitor codesign verification failures and Gatekeeper events in system.log and the Unified Logging subsystem.
Correlate process execution with TCC database (TCC.db) access attempts to identify apps reading protected data without approval.

Monitoring Recommendations

Enable endpoint telemetry that records process ancestry, code signature attributes, and file access on macOS hosts.
Alert on any process reading user data directories when the process is not present in TCC authorization records.
Track macOS version distribution across the fleet to identify hosts still running pre-Tahoe 26 builds.

How to Mitigate CVE-2025-43331

Immediate Actions Required

Upgrade affected Macs to macOS Tahoe 26, which contains the additional code-signing restrictions that remediate the issue.
Audit third-party applications for bundled legacy Apple binaries and remove or replace them.
Restrict installation of untrusted applications through Mobile Device Management (MDM) allowlists.

Patch Information

Apple addressed CVE-2025-43331 in macOS Tahoe 26 by adding code-signing restrictions that prevent the downgrade path. Refer to the Apple Support Article for the full advisory and update instructions.

Workarounds

Enforce Gatekeeper in its strictest configuration and require notarization for all third-party software.
Limit user accounts to standard privileges to reduce the scope of applications that can be installed system-wide.
Deploy MDM configuration profiles that prohibit execution of unsigned or improperly signed binaries.

bash

# Verify macOS version and confirm the patched build is installed
sw_vers -productVersion

# Check Gatekeeper status
spctl --status

# Validate the code signature of an application bundle
codesign --verify --deep --strict --verbose=2 /Applications/Example.app