CVE-2026-105590Microsoft Windows Server 2016 improper certificate validation
CVE-2026-105590 is a improper certificate validation in Microsoft Windows Server 2016, rated medium (5.3 on CVSS 3.1).
Why this priority: Medium severity, with no exploitation signal.
Published · Updated · NVD status: Awaiting Analysis
What it is
TLS certificates are not checked properly, so an attacker on the path can pose as the server.
How it is reached
An attacker can exploit it over the network, with an ordinary user account, and nobody has to click anything. Success also depends on conditions the attacker does not fully control.
What an attacker gains
A successful attack can change data or behaviour. In practice, this kind of flaw lets an attacker read or tamper with traffic, or pass a forged message as genuine.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Apply the update for your edition of Microsoft Windows Server 2016. Fixed builds: Windows Server 2016: 10.0.14393.9688; Windows Server 2016 (Server Core installation): 10.0.14393.9688. Other affected products have their own fixed versions on this page.
- Until it is patched, review who holds accounts that can reach it.
Description from NVD
Improper certificate validation in Windows Active Directory Certificate Services allows an authorized attacker to bypass a security feature over a network.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- TLS termination and service-to-service channels. The flaw sits on the network path between clients and services.
- Signature checks. The flaw sits on the network path between clients and services.
Trust boundaries in play
- Authenticated network access. An account is needed, so exposure follows who can sign in: customers, partners or staff.
- On the network path between clients and services. An attacker who crosses it can read or tamper with traffic, or pass a forged message as genuine.
Questions to answer about your own systems
- Where does Microsoft Windows Server 2016 run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.