VDB-340773 · CVE-2026-20838 · GCVE-0-2026-20838

Microsoft Windows up to Server 2025 Kernel information exposure

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.4	$0-$5k	0.67

Summaryinfo

A vulnerability classified as problematic has been found in Microsoft Windows up to Server 2025. This issue affects some unknown processing of the component Kernel. Performing a manipulation results in information exposure. This vulnerability was named CVE-2026-20838. The attack needs to be approached locally. There is no available exploit. Applying a patch is the recommended action to fix this issue.

Detailsinfo

A vulnerability was found in Microsoft Windows up to Server 2025. It has been classified as problematic. This affects some unknown processing of the component Kernel. The manipulation with an unknown input leads to a information exposure vulnerability. CWE is classifying the issue as CWE-209. The product generates an error message that includes sensitive information about its environment, users, or associated data. This is going to have an impact on confidentiality. The summary by CVE is:

Generation of error message containing sensitive information in Windows Kernel allows an authorized attacker to disclose information locally.

The weakness was presented 01/13/2026 as confirmed security update guide (Website). The advisory is shared at msrc.microsoft.com. This vulnerability is uniquely identified as CVE-2026-20838. The exploitability is told 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 $0-$5k at the moment (estimation calculated on 01/16/2026). MITRE ATT&CK project uses the attack technique T1592 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.

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Productinfo

Type

Operating System

Vendor

Microsoft

Name

Windows

Version

License

commercial

Website

Vendor: https://www.microsoft.com/
Product: https://www.microsoft.com/en-us/windows

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.4

VulDB Base Score: 3.3
VulDB Temp Score: 2.9
VulDB Vector: 🔒
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 5.5
Vendor Vector (Microsoft): 🔒

CNA Base Score: 5.5
CNA Vector (Microsoft): 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

Exploitinginfo

Class: Information exposure
CWE: CWE-209 / CWE-200 / CWE-284
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

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