CVE-2026-40539

Published Sep 18, 2026 CVSS 3.1 · 7.1 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Synology
Synology diskstation Manager
Vendors & Products Synology
Synology diskstation Manager
Type Values Removed Values Added
Title Improper Certificate Validation in Synology DSM Email API Enables Remote File Access and DoS
Type Values Removed Values Added
Title Improper Certificate Validation in Synology DSM Email API Enables Remote File Access and DoS
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Weaknesses CWE-295
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
synology
Published
Updated
Sep 18, 2026, 10:40 AM
Reserved
Apr 14, 2026, 1:01 AM
Status
Awaiting Analysis
Published
Sep 18, 2026, 9:16 AM
Modified
Sep 18, 2026, 7:07 PM