Microsoft Patches Actively Exploited Outlook Flaw That Leaks NTLMv2 Hashes
Microsoft released security updates on November 10, 2026, to address CVE-2026-124194, a Moderate-severity vulnerability in Outlook that is being actively exploited. The flaw allows attackers to send crafted message files that, when opened, cause Outlook to connect to attacker-controlled servers without displaying standard warnings. This action can expose users' NTLMv2 authentication hashes, potentially enabling impersonation. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added the vulnerability to its Known Exploited Vulnerabilities catalog, requiring federal agencies to remediate by November 24, 2026. Microsoft advises all users to install the latest updates immediately, as the vulnerability affects Microsoft 365 Apps for Enterprise, Office LTSC 2021, and Office LTSC 2024.
