CVE-2026-100219: Use-After-Free Flaw in Microsoft Windows 11 version 23H2 Scores 9.8 on CVSS
A newly published critical vulnerability in Microsoft Windows 11 version 23H2 carries a CVSS score of 9.8. Here is what is affected and how to respond.
Key points
- CVE-2026-100219 affects Microsoft Windows 11 version 23H2.
- CVSS 9.8 (Critical).
- No exploitation confirmed yet.
A critical use-after-free tracked as CVE-2026-100219 has been published in the National Vulnerability Database for Microsoft Windows 11 version 23H2, with a CVSS base score of 9.8.
At a glance
- CVE
- CVE-2026-100219
- Product
- Microsoft Windows 11 version 23H2
- CVSS
- 9.8 Critical
- Weakness
- use-after-free
- Exploited
- No known exploitation
What is the vulnerability?
The NVD entry states: Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.
Affected versions
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 11 version 23H2 | before 10.0.22631.7652 |
| Microsoft | Windows 11 Version 23H2 | before 10.0.22631.7652 |
| Microsoft | Windows 11 Version 24H2 | before 10.0.26100.9711 |
| Microsoft | Windows 11 Version 25H2 | before 10.0.26200.9711 |
| Microsoft | Windows 11 version 26H1 | before 10.0.28000.3231 |
| Microsoft | Windows 11 Version 26H2 | before 10.0.26300.9711 |
| Microsoft | Windows Server 2022 | before 10.0.20348.5761 |
| Microsoft | Windows Server 2025 | before 10.0.26100.33650 |
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C.
Is it being exploited?
There is no public confirmation of exploitation at the time of publication. It does not appear in CISA's Known Exploited Vulnerabilities catalog. We will update this report if that changes.
What should you do?
- Identify whether the affected product and versions run in your environment.
- Apply the vendor update listed in the advisory as soon as it is available.
- Limit network exposure of the affected service until it is patched.
- Monitor the vendor advisory for updated guidance or exploitation reports.
What to do and how to stay safe: CVE-2026-100219
- Vulnerability severity scores ignore your specific architecture and context.
- Exploitability depends on network exposure and user behavior, not just code flaws.
- Prioritization requires continuous asset inventory and threat intelligence alignment.
Risk-based vulnerability management focuses your limited resources on the flaws that actually threaten your business. Start by mapping your critical assets and checking for active exploits to prioritize your backlog.
Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is CVE-2026-100219?
CVE-2026-100219 is a use-after-free vulnerability in Microsoft Windows 11 version 23H2.
How severe is CVE-2026-100219?
It has a CVSS score of 9.8 Critical.
Is CVE-2026-100219 being exploited?
There is no public confirmation of exploitation at the time of publication.
