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Privacy Statement Third-Party Cookies AcceptRejectManage cookies MSRC  Customer Guidance  Security Update Guide  Vulnerabilities  CVE-2026-45583 Microsoft Exchange Server Remote Code Execution Vulnerability New On this page  CVE-2026-45583  Subscribe RSS PowerShell  API  CSAF Security Vulnerability Released: Jun 9, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-45583  Impact Remote Code Execution Max Severity Important Weakness CWE-94: Improper Control of Generation of Code ('Code Injection') CVSS Source Microsoft Vector String CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/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 High Privileges Required None User Interaction Required 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 Improper control of generation of code ('code injection') in Microsoft Exchange Server allows an unauthorized attacker to execute code 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 this mean for this vulnerability? Exploitation depends on an attacker being able to place themselves in a machine‑in‑the‑middle position on the network during use of the affected script. Because this requires specific network conditions that are not commonly present, the vulnerability is more difficult to exploit than issues that can be triggered directly. How could an attacker exploit this vulnerability? An attacker who is able to intercept network traffic could interfere with the secure connection used by the Exchange migration script and inject malicious data. When the script is run during a hybrid migration, this could cause unintended commands to run on the on‑premises Exchange server with administrative permissions. Is there anything to be done in addition to installing the June 2026 security updates for my Exchange Server? Yes, Microsoft recommends that customers download and use the latest, fixed version of the Public Folder scripts. The versions of the Public Folder scripts included with Exchange Server are outdated and will be removed in a future update. Customers can download the latest version of the Public Folder scripts here. 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 Title: Release date, Content: Jun 9, 2026 Microsoft Exchange Server Subscription Edition RTM - Remote Code Execution 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 Title: Release date, Content: Jun 9, 2026 Microsoft Exchange Server 2019 Cumulative Update 15 - Remote Code Execution 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 2019 Cumulative Update 14 - Remote Code Execution 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 - Remote Code Execution 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 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