Improper Access Control in Windows CSC Service Enables Local Data Disclosure

Publication date: 2026-01-13

Last updated on: 2026-01-13

Assigner: Microsoft Corporation

Description

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

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-01-13

Last Modified

2026-01-13

Generated

2026-07-06

AI Q&A

2026-01-14

EPSS Evaluated

2026-07-05

NVD

CVE-2026-20839

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_client-side_caching_service	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-284	The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

Attack-Flow Graph

Executive Summary

This vulnerability is an improper access control issue in the Windows Client-Side Caching (CSC) Service that allows an authorized attacker to disclose information locally. [1]

Impact Analysis

An authorized attacker could exploit this vulnerability to disclose sensitive information on the local system, potentially leading to information leakage. [1]

Hi! I’m here to help you understand CVE-2026-20839. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70