← Vulnerability feed

Vulnerability record · CVE-2026-40539 · published 18 September 2026

CVE-2026-40539: Improper certificate validation vulnerability

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.

7.1 CVSS 3.1 High EPSS 0.12% · top 98.5% CWE-295 · Improper certificate validation Awaiting Analysis
7.1CVSS 3.1 base score
0.12%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
1References
18 Sep 2026Last modified by NVD

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

References

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

Track CVE-2026-40539 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2026-85102Checkpoint gaia embedded improper certificate validation vulnerabilityImproper certificate trust validation during VPN negotiation in Check Point Quantum Security Gateway may allow an unauthenticated remote attacker to …KEVEPSS 0.99%5.5CVE-2023-41991Apple iOS, iPadOS and macOS certificate validation bypassApple iOS, iPadOS and macOS contain an improper certificate validation flaw (CWE-295) that lets a malicious app bypass signature validation. Apple st…KEVEPSS 13%analysed7.8CVE-2023-20963Android WorkSource parcel mismatch local privilege escalationCVE-2023-20963 is a parcel mismatch in Android's WorkSource component that allows a local attacker to escalate privileges without additional executio…KEVEPSS 1.5%analysed8.8CVE-2022-26923Microsoft Active Directory Domain Services certificate validation privilege escalationActive Directory Domain Services fails to properly validate certificate attributes, allowing a low-privileged domain user to obtain a certificate tha…KEVEPSS 84%analysed8.0CVE-2022-20703Cisco Small Business RV Series Routers stack-based buffer overflowCVE-2022-20703 covers multiple vulnerabilities in Cisco Small Business RV160, RV260, RV340 and RV345 Series Routers, including a stack-based buffer o…KEVEPSS 9.2%analysed8.1CVE-2020-0601Windows CryptoAPI ECC certificate validation spoofing flawWindows CryptoAPI (Crypt32.dll) improperly validates Elliptic Curve Cryptography certificates, allowing a spoofed code-signing certificate to be trus…KEVEPSS 89%analysed

Source: NIST National Vulnerability Database (record CVE-2026-40539), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.