8.8High
Microsoft Windows 10 1809
CVE-2026-62817
Out-of-bounds write in Windows DNS allows an unauthorized attacker to execute code over an adjacent network.
What this means for your business
- It affects Microsoft Windows 10 1809. It matters if your company, or a supplier that handles your data, runs it.
- An attacker can use it from inside the same network, without a login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.5% chance of attack attempts being seen in the next 30 days, ranking above 42% of all known flaws.
What to do
- 1Check whether your company or your suppliers run Microsoft Windows 10 1809, and which version. The affected versions are listed further down this page.
- 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 8.8 (v3.1)
- Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness
- CWE-787
- Assigned by
- secure@microsoft.com
Dates
- Published
- 2026-08-11
- Last modified
- 2026-09-02
- Sources
- NVD
Affected products
- Microsoft Windows 10 1809- 10.0.17763.9121
- Microsoft Windows 10 21h2- 10.0.19044.7663
- Microsoft Windows 10 22h2- 10.0.19045.7663
- Microsoft Windows 11 23h2- 10.0.22631.7517
- Microsoft Windows 11 24h2- 10.0.26100.9106
- Microsoft Windows 11 25h2- 10.0.26200.9106
- Microsoft Windows 11 26h1- 10.0.28000.2704
- Microsoft Windows Server 2019- 10.0.17763.9121
- Microsoft Windows Server 2022- 10.0.20348.5440
- Microsoft Windows Server 2025- 10.0.26100.33222
As listed in the NVD configuration data. Not a statement about your estate.