CVE-2026-45647: 
Microsoft Defender for Endpoint (ATP) vulnerability analysis and mitigation

CVE-2026-45647 is a Time-of-Check Time-of-Use (TOCTOU) race condition vulnerability in Microsoft Defender for Endpoint for macOS that allows a locally authorized attacker to escalate privileges. It affects versions from 101.0.0 up to (but not including) 101.26042.0011. The vulnerability was disclosed on June 9, 2026, as part of Microsoft's June 2026 Patch Tuesday release. It carries a CVSS v3.1 base score of 7.0 (High) (MSRC, Feedly).

The vulnerability is classified as CWE-367 (Time-of-Check Time-of-Use Race Condition), where a window exists between the time a resource is checked and the time it is used, allowing an attacker to manipulate the resource in between. An attacker with low-privileged local access can exploit this race condition — potentially via symbolic link manipulation (CAPEC-27) or classic TOCTOU techniques (CAPEC-29) — to gain elevated privileges on the affected macOS system. Exploitation requires local access and low privileges, but no user interaction, and has high attack complexity due to the timing-dependent nature of race condition exploitation (Feedly, MSRC).

Successful exploitation grants an attacker high-level (likely root or system-level) privileges on the affected macOS endpoint, resulting in high confidentiality, integrity, and availability impact. A low-privileged local user could leverage this to fully compromise the system, access sensitive data, tamper with security configurations, or disable endpoint protection mechanisms. The scope is limited to the affected system (unchanged scope), but privilege escalation could facilitate further lateral movement within a network (Feedly).

There is currently no public proof-of-concept exploit and no evidence of in-the-wild exploitation for CVE-2026-45647. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The EPSS score is approximately 0.05%, reflecting a low near-term exploitation probability. The NVD SSVC assessment also classifies exploitation as "none" at this time (Feedly, MSRC).

1. Reconnaissance: Identify macOS systems running Microsoft Defender for Endpoint versions between 101.0.0 and below 101.26042.0011 with local user access.
2. Gain local access: Obtain a low-privileged local user account on the target macOS system (e.g., via phishing, credential theft, or existing access).
3. Identify the race window: Analyze the Defender for Endpoint process to identify the specific file system operation or resource check subject to the TOCTOU race condition.
4. Prepare symbolic link or file swap: Set up a malicious symbolic link or file that will be substituted during the window between the check and use operations (consistent with CAPEC-27 techniques).
5. Trigger the race condition: Repeatedly invoke the vulnerable operation while simultaneously swapping the target resource, exploiting the timing window to redirect the privileged operation to an attacker-controlled path.
6. Achieve privilege escalation: Successfully winning the race condition causes Defender for Endpoint to operate on the attacker-controlled resource with elevated privileges, resulting in local privilege escalation to root or system level (Feedly).

Microsoft has released a patch in Microsoft Defender for Endpoint for Mac version 101.26042.0011 or later, distributed as part of the June 2026 Patch Tuesday update cycle. Organizations should prioritize updating all macOS systems running Defender for Endpoint to this version or higher. As interim measures, limit local administrative access on macOS endpoints and monitor for suspicious privilege escalation activity. No configuration-based workaround has been published; patching is the recommended remediation (MSRC, Feedly).

CVE-2026-45647 was covered as part of broader June 2026 Patch Tuesday roundups by multiple security outlets including BleepingComputer, Rapid7, Zero Day Initiative, and CyberSecurityNews, though it did not receive individual focused attention given the large volume (198–206 vulnerabilities) patched in that cycle. No specific researcher commentary or notable social media discussion has been identified for this CVE specifically (BleepingComputer, Rapid7, ZDI).