F5 Labs observes lone Russian IP scanning for SmarterMail CVE-2026-24423 unauthenticated RCE, a CISA KEV-listed flaw used in ransomware
F5 Labs analyzed exploitation of CVE-2026-24423, a CVSS 9.8 unauthenticated remote code execution flaw in SmarterTools SmarterMail (CWE-306). CISA added it to the KEV catalog on February 2, 2026 and notes it has been used in ransomware campaigns. Despite public write-ups, F5 sensors saw only one IP, 193.24.123.58 (ASN 200593, Russian ISP …