CVE-2026-40539 - 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

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HIGH

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

Published Sep 18, 2026

7.1

HIGH

CVSS 3.1

EPSS 0.12%

Description

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

Vendor Synology Product DiskStation Manager (DSM) Default
affected
- Version
  7.2.1
  Status
  affected
  Constraints
  <7.2.1-69057-10
- Version
  7.2.2
  Status
  affected
  Constraints
  <7.2.2-72806-7
- Version
  7.3
  Status
  affected
  Constraints
  <7.3.2-86009-2