Frequently asked questions about CVE-2025-53786, an elevation of privilege vulnerability affecting Microsoft Exchange Server Hybrid Deployments.

CVE-2025-53786: Frequently Asked Questions About Microsoft Exchange Server Hybrid Deployment Elevation of Privilege Vulnerability

On April 18th 2025, Microsoft announced Exchange Server Security Changes for Hybrid Deployments and accompanying non-security Hot Fix. Microsoft made these changes in the general interest of improving the security of hybrid Exchange deployments. Following further investigation, Microsoft identified specific security implications tied to the guidance and configuration steps outlined in the April announcement. Microsoft is issuing CVE-2025-53786 to document a vulnerability that is addressed by taking the steps documented with the April 18th announcement. Microsoft strongly recommends reading the information, installing the April 2025 (or later) Hot Fix and implementing the changes in your Exchange Server and hybrid environment.

Microsoft has a Hot Fix available and offers additional mitigation steps to be fully protected from this vulnerability. Urgent patching is recommended by CISA and Microsoft

Microsoft has a Hot Fix available and offers additional mitigation steps to be fully protected from this vulnerability. Urgent patching is recommended

The Microsoft Exchange Server installed on the remote host is missing a security update. It is, therefore, affected by multiple vulnerabilities as referenced in the August, 2025 security bulletin.

  - On April 18th 2025, Microsoft announced Exchange Server Security Changes for Hybrid Deployments and     accompanying non-security Hot Fix. Microsoft made these changes in the general interest of improving the     security of hybrid Exchange deployments. Following further investigation, Microsoft identified specific     security implications tied to the guidance and configuration steps outlined in the April announcement.
    Microsoft is issuing CVE-2025-53786 to document a vulnerability that is addressed by taking the steps     documented with the April 18th announcement. Microsoft strongly recommends reading the information,     installing the April 2025 (or later) Hot Fix and implementing the changes in your Exchange Server and     hybrid environment. (CVE-2025-53786)

  - Exposure of sensitive information to an unauthorized actor in Microsoft Exchange Server allows an     unauthorized attacker to disclose information over a network. (CVE-2025-33051)

  - Improper input validation in Microsoft Exchange Server allows an authorized attacker to perform tampering     over a network. (CVE-2025-25005)

  - Improper handling of additional special element in Microsoft Exchange Server allows an unauthorized     attacker to perform spoofing over a network. (CVE-2025-25006)

  - Improper validation of syntactic correctness of input in Microsoft Exchange Server allows an unauthorized     attacker to perform spoofing over a network. (CVE-2025-25007)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Microsoft Exchange Server installed on the remote host is missing a security update. It is, therefore, affected by a vulnerability as referenced in the April 2025 security bulletin.

  - Microsoft Exchange Server Hybrid Deployment Elevation of Privilege Vulnerability (CVE-2025-53786)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
249140	Security Updates for Microsoft Exchange Server (August 2025)	Nessus	Windows : Microsoft Bulletins	high
245204	Security Updates for Microsoft Exchange Server (April 2025)	Nessus	Windows : Microsoft Bulletins	high

Detections

Analytics

CVE-2025-53786

high

Tenable Plugins

high

high