CVE-2026-40539

high

Assigned by CNA: synology

Published 2026-09-18 · Modified 2026-09-18

Discuss on Community Propose mitigation

CVSS v3

7.1

CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v4 NEW

—

not yet in upstream

VIR risk

7.1

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.

Predictions

Exploit likelihood

70%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

References

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

CWEs

CWE-295

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.