CVE-2025-53786: exchange server Auth Bypass — Fix

Description

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.

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CVSS v3.1 Score

8.0

HIGH

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

Weakness Type (CWE)

CWE-287 Improper Authentication

Affected Products

Vendor	Product	Versions
microsoft	exchange_server	All
microsoft	exchange_server	All
microsoft	exchange_server	All
microsoft	exchange_server	All

References

Advisories & Patches

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53786

Frequently Asked Questions

What is CVE-2025-53786? +

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. It has a CVSS v3.1 base score of 8.0 (HIGH).

How severe is CVE-2025-53786? +

CVE-2025-53786 has a CVSS v3.1 score of 8.0 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-53786? +

CVE-2025-53786 affects products from microsoft, specifically: exchange_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-53786? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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