---
title: Critical Microsoft Defender Flaws Let Attackers Bypass Security and Upload Malware
description: Vulnerabilities in Microsoft Defender allow hackers to bypass security, posing serious post-breach risks despite being deemed low-severity.
canonical_url: https://codekeeper.co/ticker/microsoft-defender-vulnerabilities-bypass-security
---

# Critical Microsoft Defender Flaws Let Attackers Bypass Security and Upload Malware

Vulnerabilities in Microsoft Defender allow hackers to bypass security, posing serious post-breach risks despite being deemed low-severity.

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By Content Team Oct 12, 2025

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Security researchers at InfoGuard Labs discovered serious vulnerabilities in Microsoft Defender for Endpoint that allow attackers to bypass authentication and manipulate security responses. The flaws let hackers intercept commands between Defender agents and Microsoft's cloud services using easily obtainable machine and tenant IDs from the Windows registry. Attackers can spoof isolation commands, making infected devices appear secured in Microsoft's portal while remaining compromised. They can also upload malicious files to investigation packages, potentially tricking security analysts into executing malware during incident reviews. Reported to Microsoft in July 2025, the company classified these as low-severity issues with no confirmed fixes as of October 2025, despite researchers arguing they pose significant post-breach risks. **Source:** [Cybersecurity News](https://cybersecuritynews.com/microsoft-defender-authentication-bypass/)

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