CVE-2026-43748: Apple macOS Buffer Overflow Vulnerability

CVE-2026-43748 Overview

CVE-2026-43748 is an out-of-bounds write vulnerability [CWE-787] affecting Apple macOS. A malicious application can trigger unexpected system termination by writing outside the intended memory boundary. Apple addressed the flaw with improved bounds checking in macOS Sequoia 15.7.8 and macOS Tahoe 26.6.

Critical Impact
An app running on an affected macOS system can cause unexpected system termination, resulting in denial of service and potential memory corruption that may be leveraged for further exploitation.

Affected Products

Apple macOS versions prior to Sequoia 15.7.8
Apple macOS versions prior to Tahoe 26.6
Systems referenced in Apple Support Advisory #128067 and Apple Support Advisory #128071

Discovery Timeline

2026-07-27 - CVE-2026-43748 published to NVD
2026-07-28 - Last updated in NVD database

Technical Details for CVE-2026-43748

Vulnerability Analysis

The vulnerability is an out-of-bounds write condition in a macOS component. When the affected code processes attacker-controlled input, it writes data past the allocated buffer boundary. This corrupts adjacent memory structures and destabilizes the operating system.

Apple's advisory states that an app may be able to cause unexpected system termination. The condition can be exercised by a locally installed application interacting with the vulnerable subsystem. Memory corruption of this class can also serve as a primitive for further exploitation when chained with additional flaws.

Root Cause

The root cause is insufficient bounds validation on a write operation. The vulnerable routine did not verify that the destination offset or length remained within the allocated buffer before performing the write. Apple corrected the defect by adding improved bounds checking to the affected code path.

Attack Vector

Exploitation requires an application executing on the target macOS host to submit crafted input to the vulnerable component. Successful exploitation forces system termination. Refer to the Apple advisories for the specific component and version details. No public proof-of-concept or in-the-wild exploitation is reported at this time.

Detection Methods for CVE-2026-43748

Indicators of Compromise

Unexpected kernel panics or system restarts on macOS hosts running versions earlier than Sequoia 15.7.8 or Tahoe 26.6
Crash reports in /Library/Logs/DiagnosticReports/ referencing the affected component with out-of-bounds write signatures
Repeated abnormal termination events on the same host following execution of an unfamiliar application

Detection Strategies

Inventory macOS endpoints and identify hosts running versions below the patched builds
Monitor EDR telemetry for unsigned or newly installed applications that trigger system crashes shortly after execution
Correlate ReportCrash and spindump output with process execution telemetry to identify suspect binaries

Monitoring Recommendations

Ingest macOS unified logs and crash diagnostics into a centralized SIEM for correlation across the fleet
Alert on clusters of kernel panics or forced reboots that share a common parent process or binary hash
Track installation and execution of untrusted applications on macOS endpoints, especially those without valid notarization

How to Mitigate CVE-2026-43748

Immediate Actions Required

Update all macOS Sequoia systems to version 15.7.8 or later
Update all macOS Tahoe systems to version 26.6 or later
Restrict installation of untrusted applications until patches are deployed
Verify patch deployment across managed endpoints using MDM reporting

Patch Information

Apple released fixes in macOS Sequoia 15.7.8 and macOS Tahoe 26.6. Full remediation details are documented in Apple Support Advisory #128067 and Apple Support Advisory #128071. Applying these updates is the authoritative remediation path.

Workarounds

No official workaround is published by Apple; applying the security update is the required remediation
Enforce application allowlisting via Gatekeeper and MDM policies to limit execution of untrusted binaries
Require notarized and signed applications only, and remove local administrator privileges from standard user accounts

bash

# Verify installed macOS version and confirm patch level
sw_vers -productVersion

# Trigger a software update check (requires administrative privileges)
sudo softwareupdate --list
sudo softwareupdate --install --all --restart