Is CVE-2026-40539 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-40539 being exploited in the wild.

How severe is CVE-2026-40539?

High severity, with a CVSS score of 7.1, published 18 September 2026.

Which products and versions are affected?

Synology DiskStation Manager before 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2.

Is there a fix for CVE-2026-40539?

A patch was published on 2026-04-15: Fixed in DSM 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-40539 attacked?

It is attacked from the adjacent network, in an operating system.

Am I affected by CVE-2026-40539?

Check whether you run Synology DiskStation Manager at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-40539: Synology DiskStation Manager improper certificate validation in Email API

CVE-2026-40539 · Severity: high · CVSS 7.1 · Published 2026-09-18

Synology DiskStation Manager (DSM) is the operating system for Synology NAS storage devices used in enterprises and homes to manage data and backups. A flaw in the Email API's certificate validation allows attackers conducting man-in-the-middle attacks to intercept communications, read or modify files on the NAS, and trigger denial-of-service events. This requires network proximity and user interaction but can bypass encryption protections.

Technologies: Synology DiskStation Manager. Vendors: Synology.

Quick answers

Is CVE-2026-40539 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-40539 being exploited in the wild.
How severe is CVE-2026-40539?: High severity, with a CVSS score of 7.1, published 18 September 2026.
Which products and versions are affected?: Synology DiskStation Manager before 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2.
Is there a fix for CVE-2026-40539?: A patch was published on 2026-04-15: Fixed in DSM 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-40539 attacked?: It is attacked from the adjacent network, in an operating system.
Am I affected by CVE-2026-40539?: Check whether you run Synology DiskStation Manager at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

CVE-2026-40539 is an improper certificate validation vulnerability (CWE-295) in the Email API component of Synology DSM. The vulnerability allows man-in-the-middle (MITM) attackers to intercept and manipulate Email API communications due to insufficient certificate validation. Attack preconditions include network adjacency and user interaction (UI:R). Successful exploitation enables attackers to read or write arbitrary files on the affected DSM system and launch denial-of-service attacks. Patches are available: DSM 7.2.1-69057-10, DSM 7.2.2-72806-7, and DSM 7.3.2-86009-2 or later.

Affected products

Synology DiskStation Manager before 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2

Timeline

2026-09-18: disclosed: CVE published
2026-04-15: advisory: Synology advisory SA_26_06 published
2026-04-15: patched: Fixed in DSM 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2

References

https://www.synology.com/en-global/security/advisory/Synology_SA_26_06

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.