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TI-2021-08238 Aliases CVE-2021-26421GHSA-w6mv-8x3w-r7w5

Skype for Business and Lync Spoofing Vulnerability

Priority LOW 34Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

Skype for Business and Lync Spoofing Vulnerability

Why it matters now

EPSS 0.01411 72nd percentileScored 2026-11-07
Fix Fixed Skype for Business Server 2015 CU11 (Microsoft): 2046.369Microsoft Lync Server 2013 CU10 (Microsoft): 8308.1144

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
MicrosoftSkype for Business Server 2015 CU112015 CU11 to before 2046.3692046.369Patch availableCNA
MicrosoftMicrosoft Lync Server 2013 CU108308.0 to before 8308.11448308.1144Patch availableCNA
  • Skype for Business Server 2015 CU11 VendorMicrosoft Affected 2015 CU11 to before 2046.369 Fixed in 2046.369 Patch available CNA
  • Microsoft Lync Server 2013 CU10 VendorMicrosoft Affected 8308.0 to before 8308.1144 Fixed in 8308.1144 Patch available CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:microsoft:lync_server:2013:cumulative_update_10:*:*:*:*:*:*2013 cumulative_update_10VulnerableMicrosoft
cpe:2.3:a:microsoft:skype_for_business_server:2015:cumulative_update_11:*:*:*:*:*:*2015 cumulative_update_11VulnerableMicrosoft
  • cpe:2.3:a:microsoft:lync_server:2013:cumulative_update_10:*:*:*:*:*:* Versions 2013 cumulative_update_10 Vulnerable ·Microsoft
  • cpe:2.3:a:microsoft:skype_for_business_server:2015:cumulative_update_11:*:*:*:*:*:* Versions 2015 cumulative_update_11 Vulnerable ·Microsoft

Remediation

  • Fix · CNA Skype for Business Server 2015 CU11 (Microsoft) Fixed in 2046.369
  • Fix · CNA Microsoft Lync Server 2013 CU10 (Microsoft) Fixed in 8308.1144

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-26421
  2. 2026-10-03 Alias added: GHSA-w6mv-8x3w-r7w5

References

Patch 1

  • TI-2013-01140 Microsoft Communicator 2007 R2, Lync 2010, Lync 2010 Attendee, and Lync Server 2013 do… CVSS 2.0HIGH 9.3
  • TI-2014-01426 Cross-site scripting (XSS) vulnerability in the Web Components Server in Microsoft Lync… CVSS 2.0MEDIUM 4.3
  • TI-2014-03321 The Server in Microsoft Lync Server 2013 allows remote attackers to cause a denial of… CVSS 2.0MEDIUM 5.0
  • TI-2014-03319 The Response Group Service in Microsoft Lync Server 2010 and 2013 and the Core Components… CVSS 2.0MEDIUM 5.0
  • TI-2022-14751 Skype for Business and Lync Remote Code Execution Vulnerability CVSS 3.1HIGH 7.2
  • TI-2021-08239 Skype for Business and Lync Remote Code Execution Vulnerability CVSS 3.1HIGH 7.2
See all 15 →

Sources

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