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Privacy Statement Third-Party Cookies AcceptRejectManage cookies MSRC  Customer Guidance  Security Update Guide  Vulnerabilities  CVE-2026-45504 Microsoft Exchange Server Elevation of Privilege Vulnerability New On this page  CVE-2026-45504  Subscribe RSS PowerShell  API  CSAF Security Vulnerability Released: Jun 9, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-45504  Impact Elevation of Privilege Max Severity Important Weakness CWE-918: Server-Side Request Forgery (SSRF) CVSS Source Microsoft Vector String CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C Metrics CVSS:3.1 8.8 / 7.7  Base score metrics: 8.8 / Temporal score metrics: 7.7  Expand all  Collapse all Metric Value   Base score metrics(8) Attack Vector Network Attack Complexity Low Privileges Required Low User Interaction None Scope Unchanged Confidentiality High Integrity High 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 Server-side request forgery (ssrf) in Microsoft Exchange Server allows an authorized attacker to elevate privileges 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 Unlikely FAQ What privileges could be gained by an attacker who successfully exploited the vulnerability? An attacker could gain elevated privileges beyond those normally available to them, allowing actions such as accessing restricted information or performing operations that are typically limited to more highly privileged users or administrators. How could an attacker exploit this vulnerability? An attacker with a low-privilege user account and an assigned mailbox, could exploit weaknesses in how Exchange validates requests and identity tokens to impersonate another user. By doing so, the attacker could then access mailboxes through Exchange services as if they were that user. Acknowledgements MARIOS GYFTOS 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: Jun 9, 2026 Microsoft Exchange Server 2019 Cumulative Update 14 - Elevation of Privilege Important Title: Knowledge Base Articles for Microsoft Exchange Server 2019 Cumulative Update 14, Content:, 1 link 5094142  Title: Download Security Update for Microsoft Exchange Server 2019 Cumulative Update 14, Content:, 1 link Security Update Title: Build numbers, Content: 15.02.1544.041 Title: Assigning CNA, Content: Microsoft Title: Release date, Content: Jun 9, 2026 Microsoft Exchange Server 2016 Cumulative Update 23 - Elevation of Privilege Important Title: Knowledge Base Articles for Microsoft Exchange Server 2016 Cumulative Update 23, Content:, 1 link 5094144  Title: Download Security Update for Microsoft Exchange Server 2016 Cumulative Update 23, Content:, 1 link Security Update Title: Build numbers, Content: 15.01.2507.069 Title: Assigning CNA, Content: Microsoft Title: Release date, Content: Jun 9, 2026 Microsoft Exchange Server 2019 Cumulative Update 15 - Elevation of Privilege Important Title: Knowledge Base Articles for Microsoft Exchange Server 2019 Cumulative Update 15, Content:, 1 link 5094140  Title: Download Security Update for Microsoft Exchange Server 2019 Cumulative Update 15, Content:, 1 link Security Update Title: Build numbers, Content: 15.02.1748.046 Title: Assigning CNA, Content: Microsoft Title: Release date, Content: Jun 9, 2026 Microsoft Exchange Server Subscription Edition RTM - Elevation of Privilege Important Title: Knowledge Base Articles for Microsoft Exchange Server Subscription Edition RTM, Content:, 1 link 5094139  Title: Download Security Update for Microsoft Exchange Server Subscription Edition RTM, Content:, 1 link Security Update  Title: Build numbers, Content: 15.02.2562.043 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 Jun 9, 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