CVE-2026-83646

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Open Redirect Vulnerability in Active Directory Federation Services

Publication date: 2026-10-13

Last updated on: 2026-10-16

Assigner: Microsoft Corporation

Description

Url redirection to untrusted site ('open redirect') in Active Directory Federation Services (AD FS) allows an authorized attacker to perform spoofing over a network.

CVSS Scores

EPSS Scores

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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-2026-83646

EUVD

EUVD-2026-99311

Affected Vendors & Products

Vendor	Product	Version / Range
Microsoft	Windows	10 Version 1607 10.0.14393.0
Microsoft	Windows	10 Version 1809 10.0.17763.0
Microsoft	Windows	Server 2016 10.0.14393.0
Microsoft	Windows	Server 2016 (Server Core installation) 10.0.14393.0
Microsoft	Windows	Server 2019 10.0.17763.0
Microsoft	Windows	Server 2019 (Server Core installation) 10.0.17763.0
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-601	The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

Attack-Flow Graph

Executive Summary

This vulnerability is an open redirect flaw in Active Directory Federation Services (AD FS). It allows an authorized attacker to manipulate URL redirections to untrusted sites, enabling spoofing attacks over a network.

Impact Analysis

An attacker could trick users into visiting malicious sites by redirecting them from a trusted AD FS domain. This may lead to credential theft, phishing attacks, or malware infections.

Compliance Impact

This vulnerability enables spoofing attacks through open redirect in AD FS, which could allow unauthorized access to sensitive data. This may violate compliance requirements under GDPR (data protection) and HIPAA (healthcare data security) by enabling phishing attacks that compromise user credentials or personal information.

Mitigation Strategies

Apply the latest security updates from Microsoft for AD FS to address the open redirect vulnerability. Monitor Microsoft's security advisories for patches and follow their recommended mitigation steps.

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