Microsoft warns of Exchange zero-day flaw exploited in attacks
Summary
Microsoft has issued a warning about a critical zero-day vulnerability in Exchange Server that is actively being exploited in attacks. The flaw allows threat actors to execute arbitrary code through cross-site scripting (XSS) targeting users of Outlook on the web.
IFF Assessment
This vulnerability allows attackers to execute arbitrary code, posing a significant risk to organizations and their data.
Severity
The CVSS score is estimated based on the description of a high-severity vulnerability that allows arbitrary code execution via XSS, impacting confidentiality, integrity, and availability, and is actively exploited.
Defender Context
This actively exploited zero-day in Exchange Server requires immediate attention. Defenders should prioritize applying mitigations and monitoring for signs of compromise targeting Outlook on the web users. This highlights the ongoing threat of novel vulnerabilities being weaponized before official patches are available.