7.1

CVE-2026-40539: synology diskstation manager (dsm) Improper Certificate Validation

CVSS: 7.1v3.1HighAwaiting analysis
Published 18-09-2026Last modified 18-09-2026
Open JSON

Vulnerability summary

CVE-2026-40539 is a high (CVSS 7.1) Improper Certificate Validation vulnerability in synology diskstation manager (dsm). EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.5% of scored vulnerabilities.

Overall risk
28/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.1/10
010
High · v3.1 (CVE.org)
EPSS score
0.12%
0%100%
Low · +0.04 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 18-09-2026
    PublishedVulnerability first disclosed.
  2. 18-09-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.12%

Chance of exploitation in the next 30 days

Percentile

2%

Versus all other CVEs

30-day change

+0.04 pp

From 0.08% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.12%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Synology1 product

1 vendor · 1 product

References

1 links