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Elevation of Privilege in Windows Routing and Remote Access Service (RRAS)

IdentifiersCVE-2026-20843CWE-284· Improper Access Control

CVE-2026-20843 is an elevation-of-privilege vulnerability in Windows Routing and Remote Access Service (RRAS). The issue is described as improper access control in RRAS that allows an authorized attacker to elevate privileges locally. Microsoft rated the issue 7.8 CVSS and identified it as one of the January 2026 Patch Tuesday vulnerabilities that were considered more likely to be exploited. Available reporting indicates the flaw affects local authorization and access-control enforcement within the RRAS component, but the specific vulnerable function or code path is not provided in the supplied content.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows a local, authorized attacker to elevate privileges to SYSTEM on the affected Windows host. This can enable full compromise of the local system, including execution of code with highest local privileges, disabling or bypassing local protections, credential and sensitive data access, persistence, and use of the compromised host for follow-on activity.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by limiting local access to affected systems to only trusted administrators and users, minimizing the number of accounts with interactive logon capability, and restricting use of systems where RRAS is installed or enabled. Monitor for suspicious local privilege-escalation behavior and anomalous activity involving RRAS-related processes or services. No specific vendor mitigation beyond patching is provided in the supplied content.

Remediation

Patch, then assume compromise.

Apply the Microsoft security updates released as part of the January 2026 Patch Tuesday that address CVE-2026-20843 in Windows RRAS. Standard remediation is to deploy the relevant cumulative/security update to all affected Windows systems and verify successful installation through normal patch validation processes.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Microsoft CorporationWindows 10 1607operating_system
Microsoft CorporationWindows 10 1809operating_system
Microsoft CorporationWindows 10 21h2operating_system
Microsoft CorporationWindows 10 22h2operating_system
Microsoft CorporationWindows 11 23h2operating_system
Microsoft CorporationWindows 11 24h2operating_system
Microsoft CorporationWindows 11 25h2operating_system
Microsoft CorporationWindows Server 2008operating_system
Microsoft CorporationWindows Server 2008 R2operating_system
Microsoft CorporationWindows Server 2008 Sp2operating_system
Microsoft CorporationWindows Server 2012operating_system
Microsoft CorporationWindows Server 2012 R2operating_system
Microsoft CorporationWindows Server 2016operating_system
Microsoft CorporationWindows Server 2019operating_system
Microsoft CorporationWindows Server 2022operating_system
Microsoft CorporationWindows Server 2022 23h2operating_system
Microsoft CorporationWindows Server 2025operating_system
Microsoft CorporationWindows Server 23h2operating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1

Community discussion across Reddit, Mastodon, and other social sources.