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Privacy Statement Third-Party Cookies AcceptRejectManage cookies MSRC  Customer Guidance  Security Update Guide  Vulnerabilities  CVE-2026-84003 Microsoft Authentication Library (MSAL) for Node.js Spoofing Vulnerability New On this page  CVE-2026-84003  Subscribe RSS PowerShell  API  CSAF Security Vulnerability Released: Sep 8, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-84003  Impact Spoofing Max Severity Important Weakness CWE-294: Authentication Bypass by Capture-replay CVSS Source Microsoft Vector String CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C Metrics CVSS:3.1 7.4 / 6.4  Base score metrics: 7.4 / Temporal score metrics: 6.4  Expand all  Collapse all Metric Value   Base score metrics(8) Attack Vector Network Attack Complexity High Privileges Required None User Interaction None Scope Unchanged Confidentiality High Integrity High Availability None   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 Authentication bypass by capture-replay in Microsoft Authentication Library (MSAL) for Node.js allows an unauthorized attacker to perform spoofing 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 metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? Successful exploitation requires an attacker to first obtain a valid ID token issued for the victim and the same application, and then replay it through a separate authentication flow. These prerequisites make exploitation more difficult. What action should customers take to address this vulnerability? Customers should update the @azure/msal-node dependency in each affected application to version 5.6.0 or a later compatible version. From the application's project directory, run npm install @azure/msal-node@^5.6.0 --save, then rebuild, test, and redeploy the application using the organization's standard deployment process. See the MSAL Node v5.6.0 release notes and the @azure/msal-node package on npm for additional information. According to the CVSS metrics, successful exploitation of this vulnerability could lead to major loss of confidentiality (C:H), and integrity (I:H), but could lead to no loss of availability (A:N). What does that mean for this vulnerability? Exploiting this vulnerability could allow an attacker to view highly sensitive user information and modify data, but they cannot affect the availability of the service. Acknowledgements - 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 Title: Release date, Content: Sep 8, 2026 Microsoft Authentication Library (MSAL) for Node.js - Spoofing Important Title: Knowledge Base Articles for Microsoft Authentication Library (MSAL) for Node.js, Content:, 1 link Release Notes  Title: Download Security Update for Microsoft Authentication Library (MSAL) for Node.js, Content:, 1 link Security Update  Title: Build numbers, Content: 5.6.0 Title: Assigning CNA, Content: Microsoft All results loaded Loaded all 1 rows 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 Sep 8, 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