CVE-2026-20839CWE-284broken-access-control

CVE-2026-20839

Medium · published January 13, 2026

CVSS v3.1
5.5
EPSS
0%
Percentile
40.2
In the wild
Unconfirmed
What it is

Improper access control in Windows Client-Side Caching (CSC) Service allows an authorized attacker to disclose information locally.

The record
Technical detail
CVSS v3.1
5.5 · MEDIUM
Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00476 · 40.2th percentile
Weakness
CWE-284 · Improper Access Control
Published
2026-01-13T23:16Z
Affected products (17)
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_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)
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20839 · [email protected]
EPSS history
Timeline
  • 13 JAN 17:56Z
    Windows Client-Side Caching (CSC) Service Information Disclosure Vulnerability
    cvelistv5