SmarterMail authentication bypass vulnerability exploited more than 1000 times in two weeks

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Ransomware Exploits Critical SmarterMail Vulnerability CVE-2026-24423 A critical vulnerability in SmarterTools' SmarterMail, identified as CVE-2026-24423, is being actively exploited in ransomware attacks. The flaw allows unauthenticated remote code execution via malicious HTTP requests, affecting users of the email and collaboration server. CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on February 5, 2026. 35 sources 69