CVE-2026-64731 Overview
CVE-2026-64731 is a path handling vulnerability in Apple macOS that allows a malicious application to escape its sandbox. Apple addressed the flaw through improved path validation in macOS Sequoia 15.7.8 and macOS Tahoe 26.6. The weakness is classified under [CWE-22] (Improper Limitation of a Pathname to a Restricted Directory), commonly known as path traversal.
A sandbox escape defeats one of macOS's primary defense-in-depth mechanisms. Once outside the sandbox, an app can access files, resources, and system interfaces normally restricted by the App Sandbox and Mandatory Access Control layers.
Critical Impact
A malicious app can break out of its sandbox on unpatched macOS systems, gaining broader access to the host and undermining a core macOS isolation boundary.
Affected Products
- Apple macOS Sequoia prior to 15.7.8
- Apple macOS Tahoe prior to 26.6
- Applications relying on the macOS App Sandbox for isolation
Discovery Timeline
- 2026-07-27 - CVE-2026-64731 published to NVD
- 2026-07-28 - Last updated in NVD database
Technical Details for CVE-2026-64731
Vulnerability Analysis
The vulnerability lies in how macOS validated file system paths supplied by sandboxed processes. Insufficient validation permitted a crafted path to reference locations outside the sandbox container. When the operating system resolved the path, it granted access as though the target resided within the permitted scope.
Apple's advisory describes the fix as "improved validation" of paths. This wording indicates the pre-patch code trusted path components that could resolve, through traversal sequences or link indirection, to files outside the app's allowed root. Exploitation yields file access, and depending on the reached resource, code execution or privilege escalation paths become available.
The issue is tracked in Apple Support documents 128067 and 128071.
Root Cause
The root cause is improper canonicalization of file paths crossing the sandbox boundary. Path normalization did not fully account for traversal patterns or link resolution before authorization checks were applied. This mismatch between the path used for authorization and the path used for access is a classic [CWE-22] pattern.
Attack Vector
An attacker distributes a malicious application to the target macOS system. The app runs inside the standard App Sandbox and issues file operations with crafted paths designed to resolve outside the container. Successful traversal reaches system directories or another app's private data, breaking process isolation without requiring user privileges beyond running the app.
No verified public proof-of-concept is available. See the Apple Support Document #128067 and Apple Support Document #128071 for vendor technical details.
Detection Methods for CVE-2026-64731
Indicators of Compromise
- Sandboxed applications performing file system operations that resolve to paths outside their container directory under ~/Library/Containers/<bundle-id>/.
- Unexpected access to system paths such as /Library/, /private/var/, or other users' home directories by processes with the sandbox entitlement.
- Creation or traversal of symbolic links inside container directories immediately followed by cross-boundary file access.
Detection Strategies
- Monitor Endpoint Security framework events (ES_EVENT_TYPE_NOTIFY_OPEN, ES_EVENT_TYPE_NOTIFY_RENAME) for sandboxed processes accessing paths outside their expected container.
- Alert on sandbox violation entries in system.log and Unified Logging with subsystem com.apple.sandbox.
- Correlate application code signing identity and entitlements with observed file access ranges to surface anomalies.
Monitoring Recommendations
- Baseline legitimate file access patterns per bundle identifier and flag deviations from that baseline.
- Track macOS version inventory to identify hosts still running builds prior to 15.7.8 or 26.6.
- Retain process, file, and code signing telemetry centrally so path traversal chains can be reconstructed after the fact.
How to Mitigate CVE-2026-64731
Immediate Actions Required
- Update all macOS Sequoia endpoints to 15.7.8 and macOS Tahoe endpoints to 26.6 using Software Update or MDM policy.
- Audit installed applications and restrict execution to signed, notarized software from trusted sources.
- Review third-party sandboxed apps that handle untrusted input for suspicious update or execution activity.
Patch Information
Apple resolved CVE-2026-64731 in macOS Sequoia 15.7.8 and macOS Tahoe 26.6. Details are published in Apple Support Document #128067 and Apple Support Document #128071. Applying these updates is the authoritative remediation.
Workarounds
- No vendor-supplied workaround exists; patching is the only supported remediation.
- Reduce exposure by limiting installation of untrusted applications and enforcing Gatekeeper and notarization requirements via MDM.
- Constrain user privileges so that any post-escape actions face additional access control layers.
# Verify the macOS build meets the patched version
sw_vers -productVersion
# Trigger a software update check
sudo softwareupdate --list
sudo softwareupdate --install --all --restart
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
