Vulnerability in Synology Diskstation Manager (Dsm)

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.

Vulnerability class: Improper Certificate Validation

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.001 (1.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 1.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-40539: held from 0.001 to 0.001.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-40539?
CVE-2026-40539 is a high-severity vulnerability in Synology Diskstation Manager (Dsm), classified under Improper Certificate Validation. CVSS score: 7.1/10. Published 2026-09-18.
How severe is CVE-2026-40539?
High severity. CVSS v3 base score is 7.1 out of 10.