CVE-2026-65798

Windows DNS Elevation of Privilege Vulnerability

No known exploitation. EPSS puts it in the 26th percentile. A vendor fix is available.

CVSS 3.16.7Medium EPSS percentile26th0.3% chance in 30 days CISA KEVNot listedNo confirmed exploitation
No public exploit known FixVendor fixNo build named by the sources

Published 2026-08-11Updated 2026-08-17Sources: CVE.org, NVD

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

Steps

Written by AI from the record

Check which affected Windows versions you run and whether they’re fully up to date with Windows DNS/security updates.
Compare your installed build against the fixed versions for your branch; if you’re on an affected build, plan an update.
Install the Microsoft fix for CVE-2026-65798 from the Microsoft Update Guide (use Windows Update or manually apply the referenced security update).
After updating, re-check the OS build number to confirm it is at or above the fixed version for your exact edition/branch.
If patching is delayed, restrict who can log on to DNS/DNS-related systems and reduce local admin access while you prepare the upgrade.

Vendor advisory Usually a quick update

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Numeric truncation error in Windows DNS allows an authorized attacker to elevate privileges locally.

In plain language

Written by AI from the record

CVE-2026-65798 is a Windows DNS bug that can let someone with an account on your machine gain higher privileges; if you don’t have an attacker already sitting inside your network, it’s less likely, but you should still patch because it affects many supported Windows versions.

CVE-2026-65798 is a Windows DNS local elevation-of-privilege issue (CWE-197) caused by a numeric truncation problem, where an authorized attacker can elevate privileges on affected Windows 10/11 and Windows Server versions; no CISA KEV listing and no public exploit code are on record.

If you're affected

Local admin privilege escalation
Greater damage from any breach
Potential data access and tampering
Service interruption during incident

What is it

Think of Windows DNS as a “phone book” service that tells computers how to find other machines on the network. This bug is a mistake in how Windows handles a piece of information while processing DNS-related operations. If someone already has access to your machine, they may be able to use it to “level up” their permissions.

Who is affected

This matters if your business runs Microsoft Windows 10/11 or Windows Server (2012/2012 R2/2016/2019/2022/2025) systems that use Windows DNS or can be reached by a local, authorized attacker (for example, someone who already has an account on the machine). The reported risk is for an attacker who already has access—this is not described as a purely anonymous remote attack.

Reachability gate: treat this as a risk mainly when an attacker can get an authorized foothold on the affected Windows host (for example, local logon/access), not just when someone can access the network from the outside.

How urgent is it

Patch now-level urgency: this is a privilege-escalation flaw affecting core Windows components across many versions, and the overall verdict for this CVE is RED. Even though no public exploit code is known, the weakness is specifically aimed at turning an authorized foothold into higher privileges, which makes it high-value during a real intrusion.

What to do — in detail

Confirm whether you’re exposed

Identify the exact OS version/build on each relevant machine (Windows 10/11 and Windows Server 2012/2012 R2/2016/2019/2022/2025).
Determine which machines are likely to be involved with DNS (DNS server roles and systems where Windows DNS is used).

Check against fixed versions

Update targets (the system is considered fixed when it reaches the fixed build for its branch):

Windows 10 fixed in:
- 10.0.14393.9418
- 10.0.17763.9121
- 10.0.19044.7663
- 10.0.19045.7663
Windows 11 fixed in:
- 10.0.22631.7517
- 10.0.26100.9168
- 10.0.26200.9168
- 10.0.28000.2704
Windows Server fixed in:
- 2012: 6.2.9200.26280
- 2012 R2: 6.3.9600.23338
- 2016: 10.0.14393.9418
- 2019: 10.0.17763.9121

Apply the vendor fix

Use Windows Update where possible, or apply the Microsoft security update(s) referenced for this CVE.
Use the Microsoft Update Guide to select the correct update for your OS/build:
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65798
Reboot if the update requires it.
Re-check the OS build number and confirm it meets or exceeds the fixed version for your branch.

If you can’t patch immediately (temporary risk reduction)

Limit who can log on locally to the affected Windows DNS hosts and remove unnecessary local admin rights.
Reduce the number of accounts that can reach those systems, and promptly review for any suspicious activity on systems that run DNS.

What to monitor

Windows security events and sign-in/logon activity on DNS-related servers and any systems where an unauthorized party might gain local access.
Presence of unusual user behavior (new local admin creation, abnormal privilege changes) until patches are fully deployed.

(KEV note: this CVE is not listed in CISA KEV, and no public exploit code is on record, but patching is still required due to the privilege-escalation nature of the flaw.)

Technical context

CVE-2026-65798 is a Windows DNS local elevation-of-privilege vulnerability mapped to CWE-197 (numeric truncation). Findings indicate it requires an authorized attacker (i.e., not a purely unauthenticated remote attack) and that exploitation maturity is not evidenced by public exploit code on record. Patch information is available via Microsoft’s Update Guide with fixed build numbers for Windows 10/11 and Windows Server releases.

KEV: not listed in CISA KEV (so no official “known exploited” inclusion from CISA). Exploitation status: no public exploit code on record. Public reachability: local privilege escalation for an authorized attacker implies the key prerequisite is compromise or legitimate access to the target host.

EPSS: a prediction is present (flat trend), but public block guidance does not rely on it because the remediation guidance is driven by the vulnerability’s privilege-escalation impact and the assigned RED verdict.

This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS26th

CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.3% chance of exploitation activity in the next 30 days, which ranks it in the 26th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

9 events over 6 days, from the signal feeds we watch.

2026-08-17Patch availablerecord updated
2026-08-16Record updated
2026-08-13OpenVAS check added
2026-08-12Record updated
2026-08-11Publishedweakness classified, record updated, record updated

Affected products

Microsoftcommercial · US

And 25 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 6.7 by NVD.

How it is reached

Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
Attack Complexity LowNo special conditions — the attack can be reliably reproduced
Privileges Required HighRequires admin or elevated privileges
User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

Confidentiality HighTotal information disclosure — all data in the component is compromised
Integrity HighTotal loss of integrity — attacker can modify any data in the component
Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

CWE-197No name in the record

Sources

References in the record

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65798

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