CVE-2026-40539: Synology Diskstation Manager Dsm

High severity, CVSS 7.1. EPSS: 0.1% chance of exploitation in the next 30 days.

An improper certificate validation vulnerability in Email API in Synology DiskStation Manager (DSM) before 7.2.1-69057-10, 7.2.2-72806-7 and 7.3.2-86009-2 allows man-in-the-middle attackers to read or write arbitrary files and conduct denial-of-service attacks.

Affected products

• Synology Diskstation Manager Dsm: from 7.3, before 7.3.2-86009-2 (fixed in 7.3.2-86009-2); from 7.2.2, before 7.2.2-72806-7 (fixed in 7.2.2-72806-7); from 7.2.1, before 7.2.1-69057-10 (fixed in 7.2.1-69057-10)

Published 2026-09-18. Last modified 2026-09-18.