# CVE-2019-0686: Microsoft Exchange Server Elevation of Privilege Vulnerability

CVE-2019-0686 is fixed in 4 products on 1 platform, first by KB4487052, released February 12, 2019. 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-2019-0686
- Priority: Urgent
- CVSS: n/a (Important)
- EPSS: 0.0503
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: yes
- Vendor exploitability assessment: Exploitation More Likely
- Published: Feb 12, 2019
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2019-0686

## Description

<p>An elevation of privilege vulnerability exists in Microsoft Exchange Server. An attacker who successfully exploited this vulnerability could gain the same rights as any other user of the Exchange server. This could allow the attacker to perform activities such as accessing the mailboxes of other users.</p> <p>Exploitation of this vulnerability requires Exchange Web Services (EWS) and Push Notifications to be enabled and in use in an affected environment. To exploit the vulnerability, an attacker would need to execute a man-in-the-middle attack to forward an authentication request to a Microsoft Exchange Server, thereby allowing impersonation of another Exchange user.</p> <p>To address this vulnerability, Microsoft has changed the notifications contract established between EWS clients and Exchange Servers to not allow authenticated notifications to be streamed by the server. Instead, these notifications will be streamed using anonymous authentication mechanisms.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Microsoft Exchange Server 2010 Service Pack 3 Update Rollup 26 |  | [KB4487052](https://patchblox.com/security/data/fix/microsoft/kb4487052.md) | Feb 12, 2019 |
| Microsoft | Microsoft Exchange Server 2013 Cumulative Update 22 |  | [KB4345836](https://patchblox.com/security/data/fix/microsoft/kb4345836.md) | Feb 12, 2019 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 12 |  | [KB4471392](https://patchblox.com/security/data/fix/microsoft/kb4471392.md) | Feb 12, 2019 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 1 |  | [KB4471391](https://patchblox.com/security/data/fix/microsoft/kb4471391.md) | Feb 12, 2019 |

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