Microsoft has released Security Updates (SUs) for vulnerabilities found in:
- Skype for Business Server Subscription Edition (SE)
- Skype for Business Server 2019
- Skype for Business Server 2015
SUs are available for the following specific versions of Skype for Business Server:
- Skype for Business Subscription Edition (SE) CU1 Security Update 2
- Skype for Business Server 2019 CU8 Security Update 4 (to access, organization must purchase Extended Security Update (ESU))
- Skype for Business Server 2015 CU13 Security Update 4 (to access, organization must purchase Extended Security Update (ESU))
The October 2026 SUs address vulnerabilities responsibly reported to Microsoft by security partners and found through Microsoft’s internal processes.
All CVE’s associated with the public SE Security Update also apply to the SfB 2015 and SfB 2019 products under ESU.
Skype for Business 2015 and 2019 updates are available only under the Period 2 ESU program
Skype for Business Server 2015 and Skype for Business Server 2019 are out of support. Only customers who enrolled in the Period 2 Extended Security Update (ESU) program are eligible to receive Skype for Business Server 2015 and 2019 security updates released through October 2026.
If you are not part of the Period 2 ESU program, migrate to Skype for Business Server Subscription Edition (SE) to keep receiving the latest security updates.
If you have already purchased the Period 2 ESU and need information on accessing the latest Security Updates, please contact us by sending an email to Skype for BusinessandSfBServerESUInquiry@service.microsoft.com.
Skype for Business Server 2015 and 2019 Period 2 ESU Program Ends
Skype for Business Server 2015 and 2019 have been out of Support for a full year, now. October 2026 is the last month when customers who enrolled in the Period 2 Extended Security Update (ESU) program are eligible to receive Skype for Business Server 2015 and 2019 security updates.
After October 2026:
- Updates will be released for Skype for Business Server Subscription Edition (SE) only.
- Our update announcements and any CVEs released by MSRC will stop mentioning Skype for Business Server 2015 and 2019. This does not mean that those versions are not vulnerable to future security issues. We will stop testing Skype for Business Server 2015 and 2019 for vulnerabilities.
- For a limited time, the ability to purchase Period 2 ESU will remain in effect, but that will only get you current with security updates through this October release.
Please continue upgrading your organizations to Skype for Business Server SE or Teams.
The Skype for Business Team
Microsoft