Windows 11 Version 24H2: Missing Authentication for Critical Functionality
CVE-2026-85884 is a high-severity missing authentication for critical functionality vulnerability in Windows 11 Version 24H2 from Microsoft, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists version 10.0.26100.9711 as the first without the flaw, so updating Windows 11 Version 24H2 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.44% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Windows 11 Version 24H2 to 10.0.26100.9711 or a later version.
- Update Windows 11 Version 25H2 to 10.0.26200.9711 or a later version.
- Update Windows 11 version 26H1 to 10.0.28000.3231 or a later version.
- Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 up to, but not including, 10.0.26100.9711 | 10.0.26100.9711 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 up to, but not including, 10.0.26200.9711 | 10.0.26200.9711 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 up to, but not including, 10.0.28000.3231 | 10.0.28000.3231 |
| Microsoft | Windows 11 Version 26H2 | 10.0.26300.0 up to, but not including, 10.0.26300.9711 | 10.0.26300.9711 |
| Microsoft | Windows 11 24h2 | before 10.0.26100.9711 | 10.0.26100.9711 |
| Microsoft | Windows 11 25h2 | before 10.0.26200.9711 | 10.0.26200.9711 |
| Microsoft | Windows 11 26h1 | before 10.0.28000.3231 | 10.0.28000.3231 |
| Microsoft | Windows 11 26h2 | before 10.0.26300.9711 | 10.0.26300.9711 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (microsoft.com).
Official description
Missing authentication for critical function in Windows Health and Optimized Experiences Service allows an authorized attacker to elevate privileges locally.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Authentication for Critical Functionality
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
- When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data.
More Missing Authentication for Critical Functionality vulnerabilities (CWE-306)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Recent Missing Authentication for Critical Functionality vulnerabilities
- 9.8 Critical severity
- 9.6 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.7 High severity
- 9.1 Critical severity
Spotted an error? Tell us.