CVE-2026-20843CWE-284broken-access-control

CVE-2026-20843

High · published January 13, 2026

CVSS v3.1
7.8
EPSS
3%
Percentile
88.8
In the wild
Unconfirmed
What it is

⚡ An authorized user can elevate privileges on Windows RRAS with just the right moves! This access control flaw is a golden ticket for mischief! 🎟️ Think of it as someone sneaking into a VIP area at a concert using a borrowed wristband — they gain access to exclusive perks without the proper credentials! In the same way, an attacker could exploit this vulnerability to unlock unintended access to sensitive features. The consequences are serious! An attacker could gain elevated privileges, allowing them to change settings, access sensitive data, or even disable security measures. This could lead to a full compromise of the system, putting your entire network at risk!

Put simply

Think of it as someone sneaking into a VIP area at a concert using a borrowed wristband — they gain access to exclusive perks without the proper credentials! In the same way, an attacker could exploit this vulnerability to unlock unintended access to sensitive features. This vulnerability arises from improper access control in the Windows Routing and Remote Access Service (RRAS), allowing authenticated users to perform actions they shouldn't be able to, effectively elevating their privileges.

What to do

The consequences are serious! An attacker could gain elevated privileges, allowing them to change settings, access sensitive data, or even disable security measures. This could lead to a full compromise of the system, putting your entire network at risk! To mitigate this risk, ensure that all systems are updated to the latest security patches. Regularly review user permissions to ensure the principle of least privilege is enforced. Monitor for any unauthorized access attempts to your RRAS services. You've got this! By taking these steps, you can secure your systems like a champ! 🛡️

The record
Technical detail
CVSS v3.1
7.8 · HIGH
Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.03420 · 88.8th percentile
Weakness
CWE-284 · Improper Access Control
Published
2026-01-13T23:16Z
Affected products (19)
ProductVersionsFixed in
microsoft/windows_10_1607< 10.0.14393.878310.0.14393.8783
microsoft/windows_10_1607< 10.0.14393.878310.0.14393.8783
microsoft/windows_10_1809< 10.0.17763.827610.0.17763.8276
microsoft/windows_10_1809< 10.0.17763.827610.0.17763.8276
microsoft/windows_10_21h2< 10.0.19044.680910.0.19044.6809
microsoft/windows_10_22h2< 10.0.19045.680910.0.19045.6809
microsoft/windows_11_23h2< 10.0.22631.649110.0.22631.6491
microsoft/windows_11_24h2< 10.0.26100.762310.0.26100.7623
microsoft/windows_11_25h2< 10.0.26200.762310.0.26200.7623
microsoft/windows_server_2008all versions—
microsoft/windows_server_2008all versions—
microsoft/windows_server_2008all versions—
microsoft/windows_server_2012all versions—
microsoft/windows_server_2012all versions—
microsoft/windows_server_2016< 10.0.14393.878310.0.14393.8783
microsoft/windows_server_2019< 10.0.17763.827610.0.17763.8276
microsoft/windows_server_2022< 10.0.20348.464810.0.20348.4648
microsoft/windows_server_2022_23h2< 10.0.25398.209210.0.25398.2092
microsoft/windows_server_2025< 10.0.26100.3223010.0.26100.32230
References (1)
EPSS history
Timeline
  • 13 JAN 17:56Z
    Windows Routing and Remote Access Service (RRAS) Elevation of Privilege Vulnerability
    cvelistv5