We use optional cookies to improve your experience on our websites, such as through social media connections, and to display personalized advertising based on your online activity. If you reject optional cookies, only cookies necessary to provide you the services will be used. You may change your selection by clicking “Manage Cookies” at the bottom of the page. Privacy Statement Third-Party Cookies AcceptRejectManage cookies MSRC Customer Guidance Security Update Guide Vulnerabilities CVE-2026-50647 Active Directory Federation Server Denial of Service Vulnerability New On this page CVE-2026-50647 Subscribe RSS PowerShell API CSAF Security Vulnerability Released: Jul 14, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-50647 Impact Denial of Service Max Severity Important Weakness CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') CVSS Source Microsoft Vector String CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C Metrics CVSS:3.1 7.5 / 6.5 Base score metrics: 7.5 / Temporal score metrics: 6.5 Expand all Collapse all Metric Value Base score metrics(8) Attack Vector Network Attack Complexity Low Privileges Required None User Interaction None Scope Unchanged Confidentiality None Integrity None Availability High Temporal score metrics(3) Exploit Code Maturity Unproven Remediation Level Official Fix Report Confidence Confirmed Please see Common Vulnerability Scoring System for more information on the definition of these metrics. Executive Summary Loop with unreachable exit condition ('infinite loop') in Active Directory Federation Services (AD FS) allows an unauthorized attacker to deny service over a network. Exploitability The following table provides an exploitability assessment for this vulnerability at the time of original publication. Publicly disclosed No Exploited No Exploitability assessment Exploitation Less Likely FAQ According to the CVSS metrics, successful exploitation of this vulnerability could lead to major loss of availability (A:H). What does that mean for this vulnerability? An attacker can send specially crafted packets which could affect availability of the service and result in Denial of Service (DoS). Acknowledgements Anonymous Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgements for more information. Security Updates To determine the support lifecycle for your software, see the Microsoft Support Lifecycle. Release date Descending Edit columns Download Filters Product Family Max Severity Impact Platform Clear Release date Product Platform Impact Max Severity Article Download Build Number Assigning CNA Loading... Disclaimer The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. Revisions version revisionDate description 1.0 Jul 14, 2026 Information published. How satisfied are you with the MSRC Security Update Guide? Rating Broken Bad Below average Average Great! Your Privacy Choices Consumer Health Privacy Privacy & Cookies
A denial-of-service vulnerability (CVE-2026-50647, CVSS 7.5) exists in Active Directory Federation Services due to an infinite loop condition. An unauthenticated remote attacker can trigger this by sending specially crafted network packets, causing a service outage. Microsoft has released security updates to address this vulnerability; administrators should apply the patches corresponding to their AD FS versions immediately.