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Privacy Statement Third-Party Cookies AcceptRejectManage cookies MSRC  Customer Guidance  Security Update Guide  Vulnerabilities  CVE-2026-69356 Microsoft Exchange Server Spoofing Vulnerability New On this page  CVE-2026-69356  Subscribe RSS PowerShell  API  CSAF Security Vulnerability Released: Sep 8, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-69356  Impact Spoofing Max Severity Important Weakness CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CVSS Source Microsoft Vector String CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C Metrics CVSS:3.1 9.3 / 8.1  Base score metrics: 9.3 / Temporal score metrics: 8.1  Expand all  Collapse all Metric Value   Base score metrics(8) Attack Vector Network Attack Complexity Low Privileges Required None User Interaction Required Scope Changed 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 Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server 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 How could an attacker exploit this vulnerability? An unauthenticated attacker could send a specially crafted calendar invitation containing a malicious meeting link. A user would need to open the meeting and select the Join link; successful exploitation could allow script to run in the user's authenticated Outlook on the web session and access or modify mailbox data. Acknowledgements odgrso with GMO CyberSecurity by Ierae Inc https://gmo-cybersecurity.com/ 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 Exchange Server 2016 Cumulative Update 23 - Spoofing Important Title: Knowledge Base Articles for Microsoft Exchange Server 2016 Cumulative Update 23, Content:, 1 link 5121611  Title: Download Security Update for Microsoft Exchange Server 2016 Cumulative Update 23, Content:, 1 link Security Update Title: Build numbers, Content: 15.01.2507.073 Title: Assigning CNA, Content: Microsoft Title: Release date, Content: Sep 8, 2026 Microsoft Exchange Server Subscription Edition RTM - Spoofing Important Title: Knowledge Base Articles for Microsoft Exchange Server Subscription Edition RTM, Content:, 1 link 5121608  Title: Download Security Update for Microsoft Exchange Server Subscription Edition RTM, Content:, 1 link Security Update  Title: Build numbers, Content: 15.02.2562.049 Title: Assigning CNA, Content: Microsoft Title: Release date, Content: Sep 8, 2026 Microsoft Exchange Server 2019 Cumulative Update 15 - Spoofing Important Title: Knowledge Base Articles for Microsoft Exchange Server 2019 Cumulative Update 15, Content:, 1 link 5121609  Title: Download Security Update for Microsoft Exchange Server 2019 Cumulative Update 15, Content:, 1 link Security Update Title: Build numbers, Content: 15.02.1748.051 Title: Assigning CNA, Content: Microsoft Title: Release date, Content: Sep 8, 2026 Microsoft Exchange Server 2019 Cumulative Update 14 - Spoofing Important Title: Knowledge Base Articles for Microsoft Exchange Server 2019 Cumulative Update 14, Content:, 1 link 5121610  Title: Download Security Update for Microsoft Exchange Server 2019 Cumulative Update 14, Content:, 1 link Security Update Title: Build numbers, Content: 15.02.1544.046 Title: Assigning CNA, Content: Microsoft All results loaded Loaded all 4 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