VDB-363199 · CVE-2026-40408 · GCVE-0-2026-40408

Microsoft Windows up to Server 2025 WAN ARP Driver use after free

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.
7.1	$5k-$25k	0.00

Summaryinfo

A vulnerability marked as critical has been reported in Microsoft Windows. Affected by this issue is some unknown functionality of the component WAN ARP Driver. This manipulation causes use after free. The identification of this vulnerability is CVE-2026-40408. The attack can only be executed locally. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Microsoft Windows and classified as critical. Affected by this vulnerability is an unknown code of the component WAN ARP Driver. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Use after free in Windows Kernel-Mode Drivers allows an authorized attacker to elevate privileges locally.

The weakness was shared 05/12/2026 as confirmed security update guide (Website). It is possible to read the advisory at msrc.microsoft.com. This vulnerability is known as CVE-2026-40408. The exploitation appears to be easy. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 05/19/2026).

Upgrading to version 10.0.20348.5074 or 10.0.20348.5139 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability.

Be aware that VulDB is the high quality 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: 7.1

VulDB Base Score: 7.8
VulDB Temp Score: 6.8
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
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

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: Use after free
CWE: CWE-416 / CWE-119
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: Upgrade
Status: 🔍

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

Upgrade: Windows 10.0.20348.5074/10.0.20348.5139

Timelineinfo

05/12/2026 VulDB entry created
05/12/2026 +0 days Advisory disclosed
05/12/2026 +0 days Countermeasure disclosed
05/19/2026 +6 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-40408 (🔒)
GCVE (CVE): GCVE-0-2026-40408
GCVE (VulDB): GCVE-100-363199
scip Labs: https://www.scip.ch/en/?labs.20161215

Entryinfo

Created: 05/12/2026 19:47
Updated: 05/19/2026 05:08
Changes: 05/12/2026 19:47 (38), 05/12/2026 19:50 (32), 05/19/2026 05:08 (11)
Complete: 🔍
Cache ID: 216::103