# CVE-2025-53786: Microsoft Exchange Server Hybrid Deployment Elevation of Privilege Vulnerability

CVE-2025-53786 is fixed in 4 products on 1 platform, first by KB5050674, released August 12, 2025. It is not reported as exploited, but the vendor rates exploitation more likely. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2025-53786
- Priority: Urgent
- CVSS: 8.0 (Important)
- EPSS: 0.0803
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation More Likely
- Published: Aug 12, 2025
- Weakness: Improper Authentication
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53786

## Description

<p>On April 18th 2025, Microsoft announced <a href="https://techcommunity.microsoft.com/blog/exchange/exchange-server-security-changes-for-hybrid-deployments/4396833">Exchange Server Security Changes for Hybrid Deployments</a> and accompanying non-security <a href="https://techcommunity.microsoft.com/blog/exchange/released-april-2025-exchange-server-hotfix-updates/4402471">Hot Fix</a>. 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.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 23 |  | [KB5050674](https://patchblox.com/security/data/fix/microsoft/kb5050674.md) | Aug 12, 2025 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 14 |  | [KB5050673](https://patchblox.com/security/data/fix/microsoft/kb5050673.md) | Aug 12, 2025 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 15 |  | [KB5050672](https://patchblox.com/security/data/fix/microsoft/kb5050672.md) | Aug 12, 2025 |
| Microsoft | Microsoft Exchange Server Subscription Edition RTM |  | [KB5047155](https://patchblox.com/security/data/fix/microsoft/kb5047155.md) | Aug 12, 2025 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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