CVE-2026-43802: Apple macOS Buffer Overflow Vulnerability

CVE-2026-43802 Overview

CVE-2026-43802 is an out-of-bounds write vulnerability [CWE-787] affecting multiple versions of Apple macOS. Apple addressed the flaw with improved bounds checking in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, and macOS Tahoe 26.6. According to Apple's advisories, an app may be able to cause unexpected system termination when the flaw is triggered. The issue is tracked across three Apple Security Advisories corresponding to the affected macOS release trains.

Critical Impact
A malicious application can trigger an out-of-bounds memory write that leads to unexpected system termination on unpatched macOS hosts, disrupting availability and potentially enabling further memory-corruption exploitation.

Affected Products

Apple macOS Sequoia prior to 15.7.8
Apple macOS Sonoma prior to 14.8.8
Apple macOS Tahoe prior to 26.6

Discovery Timeline

2026-07-27 - CVE-2026-43802 published to the National Vulnerability Database
2026-07-28 - Last updated in NVD database

Technical Details for CVE-2026-43802

Vulnerability Analysis

CVE-2026-43802 is classified as an out-of-bounds write, mapped to [CWE-787]. Apple states the underlying condition was corrected with improved bounds checking, indicating that a code path accepted attacker-influenced input without validating that a destination pointer or index remained within the allocated buffer. When exercised, the affected code writes data past the end of a legitimate memory region.

The advisories describe the observed impact as unexpected system termination triggered by a local application. Out-of-bounds writes of this class corrupt adjacent memory structures, and depending on the corrupted object, they can escalate from a stability issue into a memory-corruption primitive suitable for privilege escalation or sandbox escape. Apple's release notes do not confirm any exploitation in the wild, and no public proof-of-concept has been published.

Root Cause

The root cause is missing or insufficient bounds validation on a write operation inside a macOS system component. The fix in 15.7.8, 14.8.8, and 26.6 introduces additional bounds checking so that write offsets and lengths are constrained to the target allocation. Apple's advisories do not name the specific subsystem in the public text.

Attack Vector

According to Apple, exploitation requires the ability to run an application on the target macOS system. A locally executing process invokes the vulnerable interface with crafted input, causing the out-of-bounds write and resulting in system termination. The delivery path in practice mirrors other macOS local-app issues: a user runs a malicious or trojanized application, or an attacker chains this flaw with a code-execution primitive obtained elsewhere.

No verified code examples are available for CVE-2026-43802. Refer to the Apple Security Advisory #128067, Apple Security Advisory #128071, and Apple Security Advisory #128072 for the authoritative vendor description.

Detection Methods for CVE-2026-43802

Indicators of Compromise

Unexpected kernel panics or system terminations logged in /Library/Logs/DiagnosticReports/ shortly after launching an unfamiliar application.
Crash reports referencing memory corruption signatures such as EXC_BAD_ACCESS, KERN_INVALID_ADDRESS, or heap corruption within Apple system frameworks.
Newly installed or recently executed unsigned binaries preceding repeated system reboots on the same host.

Detection Strategies

Inventory macOS endpoints and flag any host running a build older than 15.7.8, 14.8.8, or 26.6 as exposed.
Correlate application launch telemetry with subsequent panic logs to identify processes that consistently precede system termination events.
Hunt for unsigned or ad-hoc-signed applications executed by standard users, particularly those spawning short-lived children before a crash.

Monitoring Recommendations

Forward macOS unified logs and DiagnosticReports to a central SIEM to retain crash artifacts across reboots.
Alert on repeated panic or reboot events on the same endpoint within a short window, which can indicate exploitation attempts.
Track deployment status of the Apple security updates and generate a report of hosts that remain below the fixed build numbers.

How to Mitigate CVE-2026-43802

Immediate Actions Required

Install macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, or macOS Tahoe 26.6 on all affected endpoints.
Prioritize updates for developer workstations, administrator systems, and any host that regularly executes third-party or unsigned applications.
Restrict installation of untrusted applications by enforcing Gatekeeper and requiring notarized binaries.

Patch Information

Apple released fixes in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, and macOS Tahoe 26.6. Details are documented in Apple Security Advisory #128067, Apple Security Advisory #128071, and Apple Security Advisory #128072. Apply the update using Software Update or MDM-managed update commands.

Workarounds

No vendor-supplied workaround exists; patching is the supported remediation.
Limit local user privileges and block execution of unsigned applications through policy until the update is deployed.
Use MDM configuration profiles to restrict application sources to the App Store and identified developers on high-value hosts.

bash

# Verify installed macOS build and trigger update via CLI
sw_vers -productVersion
sudo softwareupdate --list
sudo softwareupdate --install --all --restart