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Vulnerability record · CVE-2017-11786 · published 13 October 2017

CVE-2017-11786: Microsoft lync authentication bypass by capture-replay vulnerability

Microsoft · Lync

Skype for Business in Microsoft Lync 2013 SP1 and Skype for Business 2016 allows an attacker to steal an authentication hash that can be reused elsewhere, due to how Skype for Business handles authentication requests, aka "Skype for Business Elevation of Privilege Vulnerability."

8.8 CVSS 3.0 High EPSS 9.4% · top 4.8% CWE-294 · Authentication bypass by capture-replay
8.8CVSS 3.0 base score, v2 9.3
9.4%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

Description

Skype for Business in Microsoft Lync 2013 SP1 and Skype for Business 2016 allows an attacker to steal an authentication hash that can be reused elsewhere, due to how Skype for Business handles authentication requests, aka "Skype for Business Elevation of Privilege Vulnerability."

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://www.securityfocus.com/bid/101156 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1039530 Third Party AdvisoryVDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-11786 PatchVendor Advisory
http://www.securityfocus.com/bid/101156 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1039530 Third Party AdvisoryVDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-11786 PatchVendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2017-11786), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.