CVE-2026-43788: Apple macOS Integer Overflow DoS Vulnerability

CVE-2026-43788 Overview

CVE-2026-43788 is an integer overflow vulnerability [CWE-190] affecting Apple macOS. Processing a maliciously crafted file may trigger the overflow, leading to a denial-of-service condition or disclosure of memory contents. Apple addressed the flaw in macOS Golden Gate 27 through improved input validation. The vulnerability requires local access and user interaction to exploit, limiting its exposure to scenarios where an attacker can deliver a crafted file to a target user.

Critical Impact
An authenticated local attacker can crash affected processes or leak sensitive memory contents by convincing a user to open a malicious file on an unpatched macOS system.

Affected Products

Apple macOS (versions prior to macOS Golden Gate 27)

Discovery Timeline

2026-09-14 - CVE-2026-43788 published to NVD
2026-09-15 - Last updated in NVD database

Technical Details for CVE-2026-43788

Vulnerability Analysis

The flaw is an integer overflow condition in a macOS file-processing component. When the affected code parses a specially crafted file, arithmetic operations on size or length fields wrap around expected numeric boundaries. The resulting undersized allocation or miscalculated offset creates memory safety issues during subsequent read or write operations.

Exploitation impacts confidentiality and availability. A successful attack can crash the parsing process, producing a denial-of-service condition. In other outcomes, the miscalculation causes the process to read beyond intended memory regions, exposing residual data from process memory to the attacker.

Apple resolved the issue in macOS Golden Gate 27 by tightening input validation on the fields responsible for the overflow. Refer to the Apple Support Article for the official advisory.

Root Cause

The root cause is missing or insufficient validation of untrusted numeric fields within a parsed file structure. Arithmetic on these fields overflows machine integer limits, producing a value that fails to represent the intended size.

Attack Vector

The attack requires local access, low privileges, and user interaction. An attacker delivers a crafted file through email, download, or shared storage. The victim opens or previews the file with an affected macOS component, triggering the overflow inside the parser.

No public proof-of-concept exploit is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. No verified exploitation code is available for this advisory. See the Apple Support Article for vendor guidance.

Detection Methods for CVE-2026-43788

Indicators of Compromise

Unexpected crashes or hangs in macOS file-parsing processes shortly after a user opens an attachment or downloaded file.
Crash reports in ~/Library/Logs/DiagnosticReports/ referencing memory access violations in file-handling components.
Anomalous file arrivals from untrusted sources followed by process termination events on the same host.

Detection Strategies

Monitor macOS endpoints for repeated process crashes tied to specific file types or applications.
Correlate file download or email attachment events with immediate process failure signals on the endpoint.
Inspect crash logs for signatures consistent with integer overflow patterns such as unusually large or negative allocation sizes.

Monitoring Recommendations

Enable centralized collection of macOS unified logs and DiagnosticReports for security analytics.
Alert on unexpected memory read faults in user-mode applications that regularly process untrusted files.
Track macOS software version inventory to identify hosts still running builds earlier than macOS Golden Gate 27.

How to Mitigate CVE-2026-43788

Immediate Actions Required

Update all affected Apple macOS systems to macOS Golden Gate 27 or later.
Prioritize patching on endpoints that routinely process files from external or untrusted sources.
Instruct users to avoid opening unexpected files delivered by email, chat, or web downloads until patching is complete.

Patch Information

Apple released the fix in macOS Golden Gate 27 by applying improved input validation to the affected parsing logic. Full patch details are available in the Apple Support Article.

Workarounds

Restrict processing of untrusted file types on unpatched systems using application allow-listing where feasible.
Route inbound files through gateway scanning that can quarantine malformed or suspicious files before delivery.
Apply least-privilege configurations so that a crash or memory disclosure yields minimal additional access.

bash

# Verify macOS build version on affected hosts
sw_vers -productVersion
softwareupdate --list
sudo softwareupdate --install --all --restart