Microsoft Windows up to Server 2025 HTTP.sys untrusted pointer dereference

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.
7.2	$0-$5k	0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in Microsoft Windows 11 24H2/11 25H2/11 26H1/Server 2022 23H2/Server 2025. This affects an unknown function in the library HTTP.sys. The manipulation results in untrusted pointer dereference. This vulnerability is identified as CVE-2026-21250. The attack is only possible with local access. Additionally, an exploit exists. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability classified as critical has been found in Microsoft Windows 11 24H2/11 25H2/11 26H1/Server 2022 23H2/Server 2025. Affected is an unknown functionality in the library HTTP.sys. The manipulation with an unknown input leads to a untrusted pointer dereference vulnerability. CWE is classifying the issue as CWE-822. The product obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Untrusted pointer dereference in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.

The weakness was released 02/10/2026 as confirmed security update guide (Website). The advisory is shared for download at msrc.microsoft.com. This vulnerability is traded as CVE-2026-21250. The exploitability is told to be easy. The attack needs to be approached locally. Technical details and a public exploit are known. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 05/13/2026).

The exploit is shared for download at exploit-db.com. It is declared as proof-of-concept.

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 Exploit-DB (52546). Once again VulDB remains the best source for vulnerability data.

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: 7.8
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.8
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

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

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

CVSSv2info

AV	AC	Au	C	I	A
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Untrusted pointer dereference
CWE: CWE-822
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Access: Public
Status: Proof-of-Concept
Download: 🔒

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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

Exploit-DB: 🔒

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Patch
Status: 🔍

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

Timelineinfo

02/10/2026 VulDB entry created
02/10/2026 +0 days Advisory disclosed
02/10/2026 +0 days Countermeasure disclosed
05/13/2026 +91 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-21250 (🔒)
GCVE (CVE): GCVE-0-2026-21250
GCVE (VulDB): GCVE-100-345276
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 02/10/2026 19:15
Updated: 05/13/2026 05:00
Changes: 02/10/2026 19:15 (36), 02/10/2026 19:18 (33), 02/11/2026 16:35 (11), 05/13/2026 05:00 (11)
Complete: 🔍
Cache ID: 216::103