# CVE-2017-11786: Skype for Business Elevation of Privilege Vulnerability

CVE-2017-11786 is fixed in 4 products on 1 platform, first by KB4011179, released October 10, 2017. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2017-11786
- Priority: High
- CVSS: n/a (Important)
- EPSS: 0.0939
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Unlikely
- Published: Oct 10, 2017
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2017-11786

## Description

<p>An elevation of privilege vulnerability exists when Skype for Business fails to properly handle specific authentication requests.</p> <p>An authenticated attacker who successfully exploited this vulnerability could steal an authentication hash that can be reused elsewhere. The attacker could then take any action that the user had permissions for, causing possible outcomes that could vary between users.</p> <p>To exploit the vulnerability, an attacker could invite a user to an instant message session while using a malicious profile image.</p> <p>The security update addresses the vulnerability by correcting how Skype for Business handles authentication requests.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Microsoft Lync 2013 Service Pack 1 (32-bit) |  | [KB4011179](https://patchblox.com/security/data/fix/microsoft/kb4011179.md) | Oct 10, 2017 |
| Microsoft | Microsoft Lync 2013 Service Pack 1 (64-bit) |  | [KB4011179](https://patchblox.com/security/data/fix/microsoft/kb4011179.md) | Oct 10, 2017 |
| Microsoft | Skype for Business 2016 (32-bit) |  | [KB4011159](https://patchblox.com/security/data/fix/microsoft/kb4011159.md) | Oct 10, 2017 |
| Microsoft | Skype for Business 2016 (64-bit) |  | [KB4011159](https://patchblox.com/security/data/fix/microsoft/kb4011159.md) | Oct 10, 2017 |

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Data as of 2026-11-07T12:40:37Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo