CVE-2026-20618: macOS Tahoe Information Disclosure Flaw

CVE-2026-20618 Overview

CVE-2026-20618 is a vulnerability in macOS Tahoe that involves improper handling of temporary files. This security flaw allows a malicious application to potentially access user-sensitive data through exploitation of the temporary file management mechanism. Apple has addressed this issue in macOS Tahoe 26.3 with improved handling of temporary files.

Critical Impact
Applications running on affected macOS systems may be able to access sensitive user data through improper temporary file handling, potentially leading to unauthorized information disclosure.

Affected Products

macOS Tahoe versions prior to 26.3

Discovery Timeline

February 11, 2026 - CVE-2026-20618 published to NVD
February 12, 2026 - Last updated in NVD database

Technical Details for CVE-2026-20618

Vulnerability Analysis

This vulnerability stems from insufficient security controls in the handling of temporary files within macOS Tahoe. When applications create or interact with temporary files, the operating system should enforce strict access controls to prevent unauthorized access to sensitive data. In this case, the temporary file handling mechanism fails to properly restrict access, creating an opportunity for malicious applications to read sensitive user information.

The vulnerability affects the data confidentiality of macOS users, as applications that should not have access to certain user data may be able to retrieve it through improperly secured temporary files. This type of flaw is particularly concerning in multi-application environments where sensitive data may be temporarily written to disk during normal operations.

Root Cause

The root cause of CVE-2026-20618 is improper handling of temporary files in macOS Tahoe. This typically involves insecure file permissions, predictable file naming conventions, or race conditions in the temporary file creation and deletion lifecycle. When temporary files are not properly secured, they can become vectors for information disclosure attacks.

Temporary file vulnerabilities often arise from:

Creation of temporary files with overly permissive access rights
Use of predictable naming patterns that allow attackers to anticipate file locations
Insufficient cleanup procedures leaving sensitive data exposed
Time-of-check to time-of-use (TOCTOU) race conditions

Attack Vector

The attack requires a malicious application to be installed and running on the target macOS system. Once present, the application can exploit the improper temporary file handling to access sensitive user data that should be protected by the operating system.

The attack scenario typically involves the malicious application monitoring temporary file locations, predicting file names, or exploiting race conditions to read data from temporary files before they are properly secured or deleted. This allows the attacker to harvest sensitive information such as authentication credentials, personal documents, or other confidential user data.

Detection Methods for CVE-2026-20618

Indicators of Compromise

Unusual file access patterns to temporary directories such as /tmp, /var/folders, or user-specific temporary locations
Applications exhibiting excessive read operations on files they did not create
Unexpected processes accessing system temporary file directories with high frequency

Detection Strategies

Monitor file system access logs for applications reading files from common temporary directories
Implement endpoint detection rules that alert on suspicious cross-application file access patterns
Deploy behavioral analysis to identify applications that access temporary files created by other processes

Monitoring Recommendations

Enable macOS unified logging with focus on file system operations involving temporary directories
Configure SentinelOne endpoint protection to monitor for suspicious file access patterns
Regularly audit installed applications for unexpected permissions or behaviors

How to Mitigate CVE-2026-20618

Immediate Actions Required

Update all macOS Tahoe systems to version 26.3 or later
Review and remove any untrusted or unnecessary applications from affected systems
Limit application installations to trusted sources such as the Mac App Store
Enable macOS security features including Gatekeeper and app sandboxing

Patch Information

Apple has released macOS Tahoe 26.3 which addresses this vulnerability with improved handling of temporary files. Users and administrators should update to this version as soon as possible. Detailed information about the security update is available in the Apple Support Article.

Workarounds

Restrict application installations to trusted, verified sources until patching is complete
Enable strict application sandboxing where supported to limit potential data access
Regularly review application permissions and revoke unnecessary file access rights
Consider implementing additional endpoint protection monitoring for temporary file access anomalies

bash

# Check current macOS version
sw_vers -productVersion

# Verify system is updated to 26.3 or later
# If version is below 26.3, update immediately via System Settings > Software Update