CVE-2026-50658 in Defender for Endpoint for Mac
Summary
by MITRE • 07/14/2026
Time-of-check time-of-use (toctou) race condition in Microsoft Defender allows an authorized attacker to elevate privileges locally.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/14/2026
A time-of-check time-of-use race condition vulnerability exists within Microsoft Defender's implementation that enables authenticated attackers to escalate privileges locally through a carefully orchestrated sequence of operations. This class of vulnerability occurs when the system performs a security check at one point in time and then subsequently uses the result of that check at a later point, creating an opportunity for malicious actors to manipulate the system state between these two phases.
The technical flaw manifests in Microsoft Defender's file access control mechanisms where the application performs a permission check on a resource before accessing it, but fails to maintain consistent validation throughout the entire operation. During this window, an attacker can modify or replace the target resource with a malicious alternative, effectively bypassing the initial security controls that were designed to prevent unauthorized access. This vulnerability specifically affects the local privilege escalation capabilities of authenticated users who possess basic system permissions.
The operational impact of this vulnerability extends beyond simple privilege escalation as it represents a fundamental weakness in Microsoft Defender's security model that could enable attackers to gain administrative privileges on affected systems. The race condition typically occurs during file scanning or analysis operations where Defender checks access permissions and then proceeds with processing, allowing for manipulation of the target file or directory between these two critical phases. This vulnerability affects Windows operating systems running Microsoft Defender as their primary antivirus solution.
Mitigation strategies should focus on implementing proper synchronization mechanisms to ensure that security checks remain valid throughout the entire operation lifecycle. System administrators should ensure that Microsoft Defender is updated with the latest patches and security releases from Microsoft, as this vulnerability would typically be addressed through firmware updates or security patches that close the race condition window. Organizations should also implement monitoring solutions to detect anomalous file system activities that might indicate exploitation attempts, particularly around the time of security checks.
This vulnerability aligns with CWE-367 which specifically addresses Time-of-Check Time-of-Use flaws in software implementations. The attack pattern follows typical privilege escalation techniques documented in the MITRE ATT&CK framework under T1068 for Local Privilege Escalation and T1548 for Abuse of Functionality, where attackers leverage system vulnerabilities to gain elevated access rights. Organizations should also consider implementing additional security controls such as file integrity monitoring, process monitoring, and privileged access management solutions to detect and prevent exploitation attempts.
The remediation process requires immediate patch deployment from Microsoft along with comprehensive system monitoring to identify any potential exploitation attempts. Security teams should conduct vulnerability assessments to determine the scope of affected systems and implement layered defense strategies including endpoint detection and response solutions that can identify suspicious behavior patterns associated with race condition exploitation attempts. Regular security updates and proper system hardening practices will help prevent similar vulnerabilities from being exploited in the future, particularly those related to improper access control and synchronization mechanisms in security software implementations.