New Windows Defender zero-day blocks Microsoft antivirus updates

Security researcher Abdelhamid Naceri, also known as Nightmare Eclipse, publicly released a new zero-day exploit targeting Microsoft Defender (Windows Defender). The exploit is capable of blocking antivirus definition and software updates, potentially leaving systems unprotected against new threats. This is not the first zero-day released by Naceri, who has a history of disclosing Microsoft vulnerabilities publicly. The vulnerability poses a significant risk as it can be used to prevent security tools from receiving critical updates. If exploited by threat actors, this could be used as a precursor to deploying malware or ransomware on systems with outdated antivirus signatures. No CVE identifier was mentioned in the article. Microsoft had not yet issued a patch at the time of publication. The public release of a working exploit increases the urgency for a fix from Microsoft.