Microsoft Windows up to Server 2025 RRAS access control

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.1$5k-$25k0.00

Summaryinfo

A vulnerability has been found in Microsoft Windows and classified as critical. This affects an unknown function of the component RRAS. This manipulation causes access control. This vulnerability is tracked as CVE-2026-20843. The attack is restricted to local execution. No exploit exists. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability classified as critical was found in Microsoft Windows. Affected by this vulnerability is an unknown part of the component RRAS. The manipulation with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Improper access control in Windows Routing and Remote Access Service (RRAS) allows an authorized attacker to elevate privileges locally.

The weakness was disclosed 01/13/2026 as confirmed security update guide (Website). The advisory is shared at msrc.microsoft.com. This vulnerability is known as CVE-2026-20843. The exploitation appears to be easy. An attack has to be approached locally. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 01/16/2026). MITRE ATT&CK project uses the attack technique T1068 for this issue.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-2169). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.8
VulDB Meta Temp Score: 7.1

VulDB Base Score: 7.8
VulDB Temp Score: 6.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 7.8
Vendor Vector (Microsoft): 🔒

CNA Base Score: 7.8
CNA Vector (Microsoft): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Access control
CWE: CWE-284 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔒
0-Day Time: 🔒
Exposure Time: 🔒

Timelineinfo

01/13/2026 VulDB entry created
01/13/2026 +0 days Advisory disclosed
01/13/2026 +0 days Countermeasure disclosed
01/16/2026 +3 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-20843 (🔒)
GCVE (CVE): GCVE-0-2026-20843
GCVE (VulDB): GCVE-100-340777
EUVD: 🔒
scip Labs: https://www.scip.ch/en/?labs.20161215

Entryinfo

Created: 01/13/2026 19:28
Updated: 01/16/2026 11:33
Changes: 01/13/2026 19:28 (36), 01/13/2026 19:31 (33), 01/14/2026 23:24 (1), 01/16/2026 11:33 (11)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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