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TI-2021-06394 Aliases CVE-2021-24099GHSA-gr3f-8f43-4w8g

Skype for Business and Lync Denial of Service Vulnerability

Priority LOW 35Published · Updated

Key facts

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

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

Summary

Skype for Business and Lync Denial of Service Vulnerability

Why it matters now

EPSS 0.03201 88th percentileScored 2026-11-07
Fix Fixed Skype for Business Server 2019 CU2 (Microsoft): publicationSkype for Business Server 2015 CU 8 (Microsoft): publication+1 more product

SSVC decision points

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

Affected products

VendorProductAffected versionsFixed inStatusSource
MicrosoftSkype for Business Server 2019 CU27.0.0 to before publicationpublicationPatch availableCNA
MicrosoftSkype for Business Server 2015 CU 82015 CU 8 to before publicationpublicationPatch availableCNA
MicrosoftMicrosoft Lync Server 2013before publicationpublicationPatch availableCNA
  • Skype for Business Server 2019 CU2 VendorMicrosoft Affected 7.0.0 to before publication Fixed in publication Patch available CNA
  • Skype for Business Server 2015 CU 8 VendorMicrosoft Affected 2015 CU 8 to before publication Fixed in publication Patch available CNA
  • Microsoft Lync Server 2013 VendorMicrosoft Affected before publication Fixed in publication Patch available CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:microsoft:lync_server:2013:*:*:*:*:*:*:*2013VulnerableMicrosoft
cpe:2.3:a:microsoft:skype_for_business_server:2015:cu8:*:*:*:*:*:*2015 cu8VulnerableMicrosoft
cpe:2.3:a:microsoft:skype_for_business_server:2019:cu2:*:*:*:*:*:*2019 cu2VulnerableMicrosoft
  • cpe:2.3:a:microsoft:lync_server:2013:*:*:*:*:*:*:* Versions 2013 Vulnerable ·Microsoft
  • cpe:2.3:a:microsoft:skype_for_business_server:2015:cu8:*:*:*:*:*:* Versions 2015 cu8 Vulnerable ·Microsoft
  • cpe:2.3:a:microsoft:skype_for_business_server:2019:cu2:*:*:*:*:*:* Versions 2019 cu2 Vulnerable ·Microsoft

Remediation

  • Fix · CNA Skype for Business Server 2019 CU2 (Microsoft) Fixed in publication
  • Fix · CNA Skype for Business Server 2015 CU 8 (Microsoft) Fixed in publication
  • Fix · CNA Microsoft Lync Server 2013 (Microsoft) Fixed in publication

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-24099
  2. 2026-10-03 Alias added: GHSA-gr3f-8f43-4w8g

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