# CVE-2026-20843: Microsoft Windows RRAS privilege escalation via improper access control

Source: https://junglewise.ai/threats/cve-2026-20843-microsoft-windows-rras-privilege-escalation-via-improper-access  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-01-13. Updated: 2026-07-30  
License: CC BY 4.0 with a link back

CVE-2026-20843 · Severity: high · CVSS 7.8 · Published 2026-01-13

A security vulnerability exists in the Windows Routing and Remote Access Service (RRAS), a component used to provide routing and VPN services. An attacker who already has basic access to a computer could exploit this flaw to gain full administrative control over the system. This could lead to unauthorized data access, installation of malicious software, or complete disruption of the affected server or workstation.

Technologies: [Microsoft Windows 11](https://junglewise.ai/threats/technologies/windows-11), [Microsoft Windows Server 2008 R2](https://junglewise.ai/threats/technologies/windows-server-2008-r2), [Microsoft Windows 10](https://junglewise.ai/threats/technologies/windows-10). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-20843 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-20843 being exploited in the wild.

**How severe is CVE-2026-20843?** High severity, with a CVSS score of 7.8, published 13 January 2026.

**Which products and versions are affected?** Microsoft Windows 11 22H3, 23H2, 24H2, 25H2; Microsoft Windows Server 2008 R2 Service Pack 1; Microsoft Windows 10 1607, 1809, 21H2, 22H2.

**Is there a fix for CVE-2026-20843?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-20843 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-20843?** Check whether you run Microsoft Windows 11, Microsoft Windows Server 2008 R2 or Microsoft Windows 10 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An improper access control vulnerability (CWE-284) exists in the Windows Routing and Remote Access Service (RRAS). The flaw allows a locally authenticated attacker with low privileges to bypass security restrictions and elevate their privileges to a higher level, potentially SYSTEM. The attack vector is local, requiring the attacker to have existing execution capabilities on the target host. Microsoft has released security updates to address this issue across multiple versions of Windows and Windows Server.

## Affected products

- Microsoft Windows 10 1607, 1809, 21H2, 22H2
- Microsoft Windows 11 22H3, 23H2, 24H2, 25H2
- Microsoft Windows Server 2008 R2 Service Pack 1

## Timeline

- 2026-01-13: disclosed
- 2026-01-13: advisory

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20843](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20843)

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