CVE-2026-83676

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Integer Underflow in Windows Installer Leads to Privilege Escalation

Publication date: 2026-10-13

Last updated on: 2026-10-16

Assigner: Microsoft Corporation

Description

Integer underflow (wrap or wraparound) in Windows Installer allows an authorized attacker to elevate privileges locally.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-10-13

Last Modified

2026-10-16

Generated

2026-10-19

AI Q&A

2026-10-14

EPSS Evaluated

2026-10-18

NVD

CVE-2026-83676

EUVD

EUVD-2026-99944

Affected Vendors & Products

Vendor	Product	Version / Range
Microsoft	Windows	10 Version 21H2 10.0.19044.0
Microsoft	Windows	10 Version 22H2 10.0.19045.0
Microsoft	Windows	11 version 23H2 10.0.22631.0
Microsoft	Windows	11 Version 23H2 10.0.22631.0
Microsoft	Windows	11 Version 24H2 10.0.26100.0
Microsoft	Windows	11 Version 25H2 10.0.26200.0
Microsoft	Windows	11 version 26H1 10.0.28000.0
Microsoft	Windows	11 Version 26H2 10.0.26300.0
Microsoft	Windows	Server 2022 10.0.20348.0
Microsoft	Windows	Server 2025 10.0.26100.0
Microsoft	Windows	Server 2025 (Server Core installation) 10.0.26100.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-122	A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
CWE-191	The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

Attack-Flow Graph

Executive Summary

This vulnerability is an integer underflow in Windows Installer that allows an authorized attacker to elevate their privileges locally. Integer underflow occurs when a calculation results in a value too small to be represented, causing it to wrap around to a large number, which can be exploited to gain higher access levels.

Impact Analysis

An attacker with local access could exploit this to gain elevated privileges on your system. This means they could perform actions requiring higher permissions, such as installing unauthorized software, accessing sensitive data, or making system changes that could compromise security.

Mitigation Strategies

Apply the latest security updates from Microsoft to patch the Windows Installer integer underflow vulnerability. Monitor Microsoft's update guide for specific patches and install them as soon as available.

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