TI-2026-72809 Aliases CVE-2026-85873 GHSA-6286-h9rv-4j7m

Skype for Business flaw lets attackers gain privileges

LOW 33CWE-639Published 2026-10-13 · Updated 2026-10-31

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: Security bypass
Confidentiality · integrity · availability: High · None · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-639.

Summary

Improper authorization in Skype for Business and Microsoft Lync affects Skype for Business Server 2015 CU13 from 9319.0 before 6.0.9319.886, 2019 CU8 from 2046.0 before 7.0.2046.583, and Subscription Edition CU1 from 2046.0 before 7.0.2046.889. The flaw is an authorization bypass through a user-controlled key (CWE-639) that lets an authorized attacker gain privileges over the network. Exploitation requires low privileges and no user interaction, and it has a high confidentiality impact.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

Improper authorization in Skype for Business and Microsoft Lync allows an authorized attacker to elevate privileges over a network.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00957 61st percentileScored 2026-11-07

Fix Fixed Skype for Business Server 2015 CU13 (Microsoft): 6.0.9319.886Skype for Business Server 2019 CU8 (Microsoft): 7.0.2046.583+1 more product

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Microsoft	Skype for Business Server 2015 CU13	9319.0 to before 6.0.9319.886	6.0.9319.886	Patch available	CNA
Microsoft	Skype for Business Server 2019 CU8	2046.0 to before 7.0.2046.583	7.0.2046.583	Patch available	CNA
Microsoft	Skype for Business Server Subscription Edition CU1	2046.0 to before 7.0.2046.889	7.0.2046.889	Patch available	CNA

Skype for Business Server 2015 CU13 VendorMicrosoft Affected 9319.0 to before 6.0.9319.886 Fixed in 6.0.9319.886 Patch available CNA
Skype for Business Server 2019 CU8 VendorMicrosoft Affected 2046.0 to before 7.0.2046.583 Fixed in 7.0.2046.583 Patch available CNA
Skype for Business Server Subscription Edition CU1 VendorMicrosoft Affected 2046.0 to before 7.0.2046.889 Fixed in 7.0.2046.889 Patch available CNA

Remediation

Upgrade Skype for Business Server 2015 CU13 to 6.0.9319.886, Skype for Business Server 2019 CU8 to 7.0.2046.583, or Skype for Business Server Subscription Edition CU1 to 7.0.2046.889.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Fix · CNA Skype for Business Server 2015 CU13 (Microsoft) Fixed in 6.0.9319.886
Fix · CNA Skype for Business Server 2019 CU8 (Microsoft) Fixed in 7.0.2046.583
Fix · CNA Skype for Business Server Subscription Edition CU1 (Microsoft) Fixed in 7.0.2046.889

Timeline

2026-10-13 Threatist record created from CVE-2026-85873
2026-10-13 Alias added: GHSA-6286-h9rv-4j7m
2026-10-16 Affected versions changed · CNA

References

Patch 1

Skype for Business Elevation of Privilege Vulnerability

TI-2026-42212 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
TI-2026-37256 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
TI-2026-26194 Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
TI-2026-16982 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
TI-2025-36863 Windows Server Update Service (WSUS) Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
TI-2025-33671 Microsoft SharePoint Server Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8

See all 18045 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences