Critical Zero-Day Vulnerabilities in Microsoft Defender Remain Unpatched Amid Active Exploitation
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Cybersecurity researchers and threat actors are converging on severe flaws within Microsoft Defender, with two critical zero-day vulnerabilities still unpatched as of mid-April 2026. While a proof-of-concept exploit has been released to highlight the severity of one flaw, active exploitation of these weaknesses continues to pose a significant risk to enterprise security. The situation underscores an ongoing arms race between defenders and attackers, where critical patches are lagging behind the deployment of malicious exploits.
Timeline
Threat Actors Exploit Unpatched Microsoft Defender Zero-Days
LONDON — Threat actors are actively exploiting three zero-day vulnerabilities in Microsoft Defender, with two of the flaws remaining unpatched as of Thursday. The cybersecurity vendor Huntress confirm...
Researcher Releases Proof-of-Concept for Microsoft Defender Zero-Day Vulnerability
WASHINGTON (April 16, 2026) — A cybersecurity researcher operating under the pseudonym Chaotic Eclipse released a proof-of-concept exploit Wednesday for a zero-day vulnerability in Microsoft Defender,...