# CVE-2019-1373: Microsoft Exchange Remote Code Execution Vulnerability

CVE-2019-1373 is fixed in 5 products on 1 platform, first by KB4523171, released November 12, 2019. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2019-1373
- Priority: Urgent
- CVSS: n/a (Critical)
- EPSS: 0.2168
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Less Likely
- Published: Nov 12, 2019
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2019-1373

## Description

<p>A remote code execution vulnerability exists in Microsoft Exchange through the deserialization of metadata via PowerShell. An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the logged in user.</p> <p>Exploitation of this vulnerability requires that a user run cmdlets via PowerShell.</p> <p>The security update addresses the vulnerability by correcting how Exchange serializes its metadata.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Microsoft Exchange Server 2013 Cumulative Update 23 |  | [KB4523171](https://patchblox.com/security/data/fix/microsoft/kb4523171.md) | Nov 12, 2019 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 13 |  | [KB4523171](https://patchblox.com/security/data/fix/microsoft/kb4523171.md) | Nov 12, 2019 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 14 |  | [KB4523171](https://patchblox.com/security/data/fix/microsoft/kb4523171.md) | Nov 12, 2019 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 2 |  | [KB4523171](https://patchblox.com/security/data/fix/microsoft/kb4523171.md) | Nov 12, 2019 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 3 |  | [KB4523171](https://patchblox.com/security/data/fix/microsoft/kb4523171.md) | Nov 12, 2019 |

---

Data as of 2026-11-07T18:46:35Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.