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CVE-2020-1025: Microsoft Office Elevation of Privilege Vulnerability

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 5.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-07-14 · updated 2026-06-17
• Weakness: CWE-20

Description

An elevation of privilege vulnerability exists when Microsoft SharePoint Server and Skype for Business Server improperly handle OAuth token validation. An attacker who successfully exploited the vulnerability could bypass authentication and achieve improper access. To exploit this vulnerability, an attacker would need to modify the token. The update addresses the vulnerability by modifying how Microsoft SharePoint Server and Skype for Business Server validate tokens.

Affected products

• Microsoft Lync Server: 2013
• Microsoft SharePoint Server: 2016
• Microsoft SharePoint Foundation 2013 Service Pack 1: 2013-sp1
• Microsoft SharePoint Server: 2019
• Microsoft Skype for Business Server 2019 CU2: 2015-cumulative_update_8, 2019-cumulative_update_2
• Microsoft Lync Server 2013: before publication — fixed in publication
• Microsoft Sharepoint Enterprise Server 2016: from 16.0.0 before publication — fixed in publication
• Microsoft SharePoint Foundation 2013 Service Pack 1: from 15.0.0 before publication — fixed in publication
• Microsoft SharePoint Server: from 16.0.0 before publication — fixed in publication
• Microsoft Skype for Business Server 2019 CU2: from 7.0.0 before publication — fixed in publication
• Microsoft Skype for Business Server 2015 CU 8: from 2015 CU 8 before publication — fixed in publication

How to fix

Upgrade to a fixed version: Microsoft Lync Server 2013 publication; Microsoft Sharepoint Enterprise Server 2016 publication; Microsoft SharePoint Foundation 2013 Service Pack 1 publication; Microsoft SharePoint Server publication; Microsoft Skype for Business Server 2019 CU2 publication; Microsoft Skype for Business Server 2015 CU 8 publication. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1025
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1025

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